Source: https://patents.google.com/patent/JP4329374B2/en
Timestamp: 2020-08-11 11:08:47
Document Index: 742657219

Matched Legal Cases: ['art.4', 'art 1', 'art 1', 'art 20', 'art 20', 'art 2', 'art 20', 'art 2', 'art.4', 'art\n2']

JP4329374B2 - Light emitting element and manufacturing method thereof - Google Patents
Light emitting element and manufacturing method thereof Download PDF
JP4329374B2
JP4329374B2 JP2003086107A JP2003086107A JP4329374B2 JP 4329374 B2 JP4329374 B2 JP 4329374B2 JP 2003086107 A JP2003086107 A JP 2003086107A JP 2003086107 A JP2003086107 A JP 2003086107A JP 4329374 B2 JP4329374 B2 JP 4329374B2
JP2003086107A
JP2004128445A (en
亮一 寺内
2002-07-29 Priority to JP2002220323 priority Critical
2003-03-26 Application filed by パナソニック電工株式会社 filed Critical パナソニック電工株式会社
2003-03-26 Priority to JP2003086107A priority patent/JP4329374B2/en
2004-04-22 Publication of JP2004128445A publication Critical patent/JP2004128445A/en
2009-09-09 Publication of JP4329374B2 publication Critical patent/JP4329374B2/en
238000000605 extraction Methods 0.000 claims description 50
230000003685 thermal hair damage Effects 0.000 claims description 43
230000001678 irradiating Effects 0.000 claims description 26
239000004038 photonic crystal Substances 0.000 claims description 22
239000000470 constituents Substances 0.000 claims description 16
229910052594 sapphire Inorganic materials 0.000 description 32
2. Description of the Related Art Conventionally, a light emitting element including a light emitting element body in which a light emitting portion made of a compound semiconductor material is formed on one surface side of a substrate has been provided, and a sapphire substrate is used as a substrate while adopting a gallium nitride material as a compound semiconductor material. There has been known a light-emitting element including a light-emitting element main body adopted. However, in such a light emitting element, the light emitted from the light emitting part is reflected at the interface due to the difference in the refractive index of the air around the light emitting part, the sapphire substrate, and the light emitting element body. There is a problem that it cannot be efficiently taken out to the outside.
Therefore, in order to improve the light extraction efficiency, a light-emitting element including a light-emitting element body A ′ configured as shown in FIG. 27 has been proposed (see, for example, Patent Document 1). In the light emitting element body A ′ having the configuration shown in FIG. 27, the light emitting section 2 including the n-type GaN layer 2a and the p-type GaN layer 2b is formed on one surface (the lower surface in FIG. 27) side of the substrate 1 made of a sapphire substrate. Thus, the light extraction efficiency to the outside is improved by suppressing the multiple reflection on the surface of the light emitting unit 2 with the surface of the light emitting unit 2 (the lower surface in FIG. 27) being a non-mirror surface. Electrodes 3a and 3b are formed on the n-type GaN layer 2a and the p-type GaN layer 2b of the light emitting section 2, respectively.
By the way, in the above publication, the following two methods have been proposed as methods for making the surface of the light emitting unit 2 non-specular. First, as a first method, a method is proposed in which the surface orientation of the one surface of the sapphire substrate as the substrate 1 is shifted by 0.2 to 1.5 ° from the C axis, and the light emitting portion 2 is formed by epitaxial growth. Yes. That is, in the first method, a so-called off-substrate is used as the substrate 1 so that the surface of the light emitting portion 2 formed by epitaxial growth is made non-specular. Next, as a second method, there has been proposed a method in which the surface of the light emitting unit 2 is made non-specular by etching or polishing the surface of the light emitting unit 2 formed so as to have a mirror surface by epitaxial growth. Yes.
JP-A-6-291368
However, in the light emitting element in which the surface of the light emitting unit 2 is made non-specular by the first method, the degree of roughening of the surface of the light emitting unit 2 is low, and the intensity of the light extracted to the outside is the surface of the light emitting unit 2 Compared to the mirror surface, the improvement is only about 10%, and further improvement in the light extraction efficiency to the outside is desired.
On the other hand, in the light emitting element in which the surface of the light emitting unit 2 is made non-mirror surface by the second method, residual stress or cracks are generated in the vicinity of the surface of the light emitting unit 2, and the reliability of the mechanical strength of the light emitting element body A ′ is improved. There was a problem that would decrease. In addition, it is difficult to adopt the second method when the light emitting element body A 'is in a chip state.
The present invention has been made in view of the above reasons, and an object of the present invention is to provide a light emitting element capable of efficiently taking out light emitted from a light emitting portion to the outside and a method for manufacturing the same.
In order to achieve the above object, a light-emitting element body in which a light-emitting portion made of a semiconductor material is formed on one surface side in the thickness direction of a substrate transparent to light emitted from the light-emitting portion. A light-emitting element that extracts light from the thickness direction of the substrate, and includes a refractive index adjustment unit having a structure in which a refractive index is changed, which includes two types of media having different refractive indexes in a plane parallel to the light-emitting unit. Within the thickness of the light-emitting element bodyOn the other surface side of the substrate.KeraThe refractive index adjusting unit is configured such that one of the two types of medium is a constituent material of the light emitting element body and the other is a material obtained by modifying the constituent material of the light emitting element body.The multiple reflection within the light emitting element body is less likely to occur, and the light extraction efficiency to the outside is improved.. In addition, since the refractive index adjusting portion is formed on the other surface side of the substrate, the light emitted from the light emitting portion is less likely to be totally reflected on the other surface side of the substrate. Further, the refractive index adjusting unit includes one of the two types of mediums that is a constituent material of the light emitting element body, and the other is a material that is a modified material of the light emitting element body. It is possible to form the refractive index adjusting portion by performing a modification process using a laser.
According to a second aspect of the present invention, in the first aspect of the invention, the refractive index adjusting unit has a periodic structure or a quasi-periodic structure of two types of media having different refractive indices in a plane parallel to the light emitting unit. The period of the structure or quasi-periodic structure is from 1/4 to the wavelength of the light emitted from the light emitting part.4 timesTherefore, the change in the refractive index in the light traveling direction can be reduced, multiple reflections within the light emitting element body are less likely to occur, and the light extraction efficiency to the outside is improved.
Claim3The invention of claim1 or claim 2In the invention, a number of fine columnar regions having different refractive indexes from the substrate reflect the light emitted from the light emitting portion to the other surface side of the substrate, and the thickness direction is a longitudinal direction of the wavelength of the light. Since the reflection part regularly arranged at intervals is provided in the substrate, the light emitted from the light emitting part can be reflected to the other surface side of the substrate, and light is emitted from the side surface of the substrate. In addition, the light can be efficiently guided to the other surface side of the substrate, and the light can be efficiently extracted from the surface parallel to the light emitting portion to the outside.
Claim4The invention of claim1 or claim 2In the invention, since the photonic crystal that adjusts the area of the light extraction surface of the light emitting element body and reflects the light from the light emitting portion toward the light extraction surface is formed in the substrate, from the side surface of the substrate Light can be prevented from being emitted, light can be efficiently guided to the light extraction surface side of the substrate, and light can be efficiently extracted from a surface parallel to the light emitting portion to the outside.
Claim5The invention of claim1 or claim 2In the invention, since the light emitting part has reflection parts regularly arranged at intervals of ½ of the wavelength of the light so as to reflect the light emitted from the light emitting part to the substrate side, the light emitting part It is possible to reflect the light emitted from the substrate to the substrate side, to efficiently guide the light to the other surface side of the substrate, and to efficiently extract the light from the surface parallel to the light emitting portion to the outside. .
Claim6The invention of claim 1 to claim 15The method of manufacturing a light-emitting element according to any one of the above, wherein in the step of forming the refractive index adjustment unit, a pulse laser having a pulse width that does not cause thermal damage to the periphery of the laser irradiation portion of the light-emitting element body is condensed. The laser irradiation portion is processed by irradiating, and the refractive index adjusting portion can be formed in a non-contact manner without any change in composition, and the light emitting element main body is heated during the formation of the refractive index adjusting portion. Since it is possible to prevent the occurrence of damage and to prevent the mechanical strength from being lowered due to the formation of the refractive index adjusting portion, the light emitting device that improves the light extraction efficiency to the outside without impairing the reliability Can be provided.
Claim7The invention of claim 1 to claim 15The method of manufacturing a light-emitting element according to any one of the above, wherein, in the step of forming the refractive index adjusting unit, a pulse laser having a pulse width that does not cause thermal damage to the periphery of the laser irradiation portion in the light-emitting element body emits the light. Forming the refractive index adjusting part in a non-contact manner without changing the composition, by simultaneously irradiating the region to be formed of the refractive index adjusting part in the element body from a plurality of directions and causing the irradiated light to interfere with each other. In addition, it is possible to prevent thermal damage to the light emitting element body during the formation of the refractive index adjusting unit, and to prevent a decrease in mechanical strength associated with the formation of the refractive index adjusting unit. In addition, a light-emitting element that improves the efficiency of extracting light to the outside without impairing reliability can be provided. Further, it is possible to collectively form the refractive index adjustment portion,6Productivity can be improved compared with the invention of the present invention.
Claim8The invention of claim3The method of manufacturing a light emitting device according to claim 1, wherein in the step of forming the reflecting portion, the laser is obtained by condensing and irradiating a pulse laser having a pulse width that does not cause thermal damage to the periphery of the laser irradiation portion in the substrate. Each of the columnar regions is formed by modifying an irradiated portion, and the reflective portion can be easily formed in a non-contact manner in the substrate, and heat is generated along with the formation of the reflective portion. Damage can be prevented from occurring.
Claim9The invention of claim4The light emitting device manufacturing method according to claim 1, wherein in the step of forming the photonic crystal, the pulse laser having a pulse width that does not cause thermal damage to the periphery of the laser irradiation portion in the substrate is focused and irradiated. The laser irradiation portion is modified, the photonic crystal can be easily formed in the substrate in a non-contact manner, and thermal damage is prevented from being caused by the formation of the photonic crystal. can do.
Claim10The invention of claim5The method of manufacturing a light emitting element according to claim 1, wherein in the step of forming the reflection portion, the laser is obtained by condensing and irradiating a pulse laser having a pulse width that does not cause thermal damage to the periphery of the laser irradiation portion in the light emission portion. The irradiation portion is modified, the reflection portion can be easily formed in a non-contact manner in the light emitting portion, and further, it is possible to prevent thermal damage from occurring due to the formation of the reflection portion. it can.
The light emitting element of this embodiment includes a light emitting element body A having the configuration shown in FIG. The light emitting element body A is a sapphire substrate (α-Al2O3A light emitting section 2 composed of an n-type GaN layer 2a and a p-type GaN layer 2b is formed on one surface (the lower surface in FIG. 1A) of the substrate 1 composed of a substrate, and the n-type GaN layer 2a and the p-type GaN are formed. Electrodes 3a and 3b are formed on the respective layers 2b. Here, the one surface of the substrate 1 is a C plane, and the light emitting portion 2 is composed of the n-type GaN layer 2a and the p-type GaN layer 2b that are epitaxially grown on the one surface side of the substrate 1. However, the structure of the light emitting unit 2 is not particularly limited, and for example, a well-known structure such as a single hetero structure or a double hetero structure may be adopted.
Note that the material of the light emitting section 2 is not particularly limited to GaN, and it goes without saying that a semiconductor material other than GaN may be adopted. The material of the substrate 1 is also Al.2O3For example, GaN, GaAs, GaP, SiC, or the like may be employed. Here, the refractive index of the substrate 1 is 1.768 when a sapphire substrate is employed, 2.00 when a GaN substrate is employed, 3.3 to 3.8 when a GaAs substrate is employed, When a GaP substrate is adopted, it becomes 3.31, and when a SiC substrate is adopted, it becomes 3.1 to 4.1. In any case, the refractive indexes of the light emitting unit 2 and the substrate 1 are larger than the refractive index of air that is a medium from which light is extracted.
In the present embodiment, since the substrate 1 used for the light emitting element body A is transparent to the light emitted from the light emitting unit 2, the light emitted from the light emitting unit 2 passes through the p-type GaN layer 2 b and the substrate 1 to the outside. It can be taken out. That is, in the light emitting element of the present embodiment, the light emitted from the light emitting unit 2 can be taken out from both sides in the thickness direction of the substrate 1 (upward direction in FIG. 1A). In the present embodiment, the surface of the p-type GaN layer 2b and the other surface of the substrate 1 (upper surface in FIG. 1A) form a light extraction surface.
By the way, the light emitting element main body A has a different refractive index in a plane parallel to the light emitting portion 2 on the other surface (upper surface in FIG. 1A) side of the substrate 1 as shown in FIGS. A refractive index adjusting unit 4 is formed which is composed of two types of media 4a and 4b and has a structure in which the refractive index is regularly changed. Here, the refractive index adjusting unit 4 has a periodic structure of two types of media 4 a and 4 b having different refractive indexes in a plane parallel to the light emitting unit 2. The medium 4 a has a cylindrical shape and is regularly arranged so as to have a two-dimensional periodic structure in a plane parallel to the light emitting unit 2. That is, the medium 4a has periodicity in each of the vertical direction and the horizontal direction in FIG.
Further, the refractive index adjusting unit 4 has a medium 4a formed by modifying and processing a part of the substrate 1 by condensing and irradiating a pulsed laser on the other surface side of the substrate 1. It is provided within the thickness dimension. In the step of forming the refractive index adjusting unit 4, the laser irradiation part is modified without changing the composition by condensing and irradiating a pulse laser having a pulse width that does not cause thermal damage to the periphery of the laser irradiation part in the substrate 1 made of the sapphire substrate. Processing. Here, if a pulse laser having a pulse width of 1 ps or less is employed, the occurrence of thermal damage around the laser irradiated portion can be prevented. Therefore, in the refractive index adjusting unit 4, one medium 4 b of the two types of media 4 a and 4 b is the constituent material of the substrate 1 (that is, the constituent material of the light emitting element body A), and the other medium 4 a is the constituent of the substrate 1. The material is a modified material.
As specific process conditions of the refractive index adjusting unit 4, a pulse laser (so-called femtosecond laser) having a laser beam wavelength of 800 nm and a pulse width of 150 fs is used, and the processing energy per pulse is about 1 μJ or less (processing energy) Is about 1 μJ / pulse or less), the medium 4a can be formed in a region having a circular shape in plan view and a diameter of about 100 nm on the other surface side of the substrate 1 made of a sapphire substrate. When the pulse width is as short as 1 ps or less, it is possible to perform processing while suppressing the thermal influence on the periphery of the laser irradiation portion, and it is also possible to perform processing with a size that is less than the diffraction limit of light. To explain further, in general, when removal processing is performed with a laser, it takes ns order time for heat to propagate around the laser irradiation portion, but in this embodiment, the laser irradiation is completed at 1 ps or less. Therefore, the processing is completed before the heat propagates to the periphery of the laser irradiation portion, and as a result, the occurrence of thermal damage to the periphery of the laser irradiation portion can be prevented. However, of course, when using a pulse laser, the pulse width that does not cause thermal damage to the periphery of the laser irradiation portion differs depending on the material to be irradiated with the pulse laser.
Thus, in this embodiment, the laser irradiation portion is modified (modified) by condensing and irradiating the other surface side of the substrate 1 with a pulse laser having a pulse width that does not cause thermal damage to the periphery of the laser irradiation portion of the substrate 1. Since the refractive index adjusting unit 4 is formed by processing), there is no thermal damage or mechanical damage around the laser irradiation portion with the formation of the refractive index adjusting unit 4, The reduction in mechanical strength of the light emitting element main body A due to the formation of the refractive index adjusting unit 4 can be prevented, and the reliability can be improved.
Further, since the laser can process the object to be processed (here, the substrate 1) in a non-contact manner and can also focus on a fine beam diameter, the refractive index is not in contact with the light-emitting element body A. The adjustment unit 4 can be formed, and the refractive index adjustment unit 4 can be formed even after the light emitting element body A is mounted on a mounting substrate (not shown).
In the light emitting device including the light emitting device main body A manufactured as described above, the provision of the refractive index adjusting unit 4 makes it difficult for multiple reflections in the light emitting device main body A to occur, and the light extraction efficiency to the outside is improved. improves.
In the present embodiment, the above-described medium 4a has a circular planar shape, but may be a rectangular planar shape as shown in FIG. 3 or a linear planar shape as shown in FIG. It is good. Here, the rectangular shape of the medium 4a as shown in FIG. 3 can be easily realized by making the laser beam profile rectangular, and the planar shape of the medium 4a is shown in FIG. Such a linear shape can be easily realized by making the beam profile of the laser rectangular and scanning the position of the condensing point on the substrate 1.
Of this reference exampleThe basic configuration of the light-emitting element is substantially the same as that of the first embodiment, and includes the light-emitting element body A having the configuration shown in FIG. 5A. As shown in FIG. The structure of the refractive index adjusting portion 4 formed on the upper surface side in FIG. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, and description is abbreviate | omitted.
In the refractive index adjusting unit 4 according to the first embodiment, one of the two types of media 4a and 4b is such that one medium 4b is the constituent material of the substrate 1 (that is, the constituent material of the light emitting element body A) and the other medium 4a is the substrate 1. Although the component material is a modified material,In this reference exampleThe refractive index adjusting unit 4 includes a concave portion 1a in which one medium 4b of the two types of media 4a and 4b is a constituent material of the substrate 1 and the other medium 4a is periodically formed on the other surface side of the substrate 1. The point which becomes the inside air is different. The formation region of the recess 1a is the same as the formation region of the medium 4a in the first embodiment.
By the way, the refractive index adjustment unit 4 is formed by condensing and irradiating a pulsed laser on the other surface side of the substrate 1 to remove a part of the substrate 1, and within the thickness dimension of the light emitting element body A. Is provided. In the step of forming the refractive index adjusting unit 4, the laser irradiation portion is removed by condensing and irradiating a pulse laser having a pulse width that does not cause thermal damage to the periphery of the laser irradiation portion in the substrate 1 made of a sapphire substrate. As in the first embodiment, if a pulse laser having a pulse width of 1 ps or less is employed, the occurrence of thermal damage around the laser irradiated portion can be prevented. In addition, by adopting a pulse laser with a pulse width of 1 ps or less, multiphoton absorption occurs, the processing object is locally heated, and the processing object can be processed, and it is difficult to remove it with the energy of one photon. Can be removed by multiphoton absorption. Also, when the laser beam is focused, it is difficult to focus the beam diameter below the wavelength of the laser, and generally it is not possible to process the size below the laser wavelength, but use multiphoton absorption. This makes it possible to perform processing with a beam diameter smaller than that of the beam. That is, it is possible to process only a part having a beam size equal to or larger than the processing threshold due to multiphoton absorption.
For example, when a Ti: sapphire laser having a laser beam wavelength of 800 nm and a pulse width of 150 fs is used as the above-described pulse laser, the processing energy per pulse is about 1 μJ (processing energy is about 1 μJ / pulse), and one pulse By processing, the concave portion 1a can be formed in a region having a circular shape in plan view and a diameter of about 100 nm on the other surface side of the substrate 1 made of a sapphire substrate (hole processing can be performed). In addition, if an excimer laser, which is an ultraviolet laser, is used, the wavelength is shorter than that of a Ti: sapphire laser, so that the photon energy is high and the laser beam can be condensed with a smaller diameter than the laser beam diameter. Processing becomes possible.
By the way, since the recess 1a has a uniform opening width in the depth direction along the thickness direction of the substrate 1, and the aspect ratio of the recess 1a that can be processed by the above-described removal processing is about 10, the depth dimension of the recess 1a is What is necessary is just to set so that the aspect ratio which consists of the ratio of the depth dimension of the recessed part 1a and the opening width (opening dimension) of the recessed part 1a may be set to about 1-10. For example, when the opening width of the recess 1a is set in the range of 0.05 to 2.0 μm, the depth dimension of the recess 1a may be set in the range of 0.05 μm to 20 μm.
ButIn this reference exampleSince the refractive index adjusting unit 4 is formed by condensing and irradiating a pulse laser having a pulse width that does not cause thermal damage to the periphery of the laser irradiation portion of the substrate 1 and removing the laser irradiation portion, the refractive index is adjusted. With the formation of the adjusting portion 4, thermal damage or mechanical damage does not occur around the laser irradiation portion, and the reliability of the light emitting element body A can be improved.
Also,Of this reference exampleAlso in the light emitting element, similarly to the first embodiment, the provision of the refractive index adjusting unit 4 makes it difficult for multiple reflections in the light emitting element body A to occur, and the light extraction efficiency to the outside is improved.
Of this reference exampleBasic structure of light emitting elementAnd Reference Example 1The light-emitting element body A is substantially the same and has the structure shown in FIG. 6A, and the structure of the refractive index adjusting unit 4 is different as shown in FIGS. 6B and 6C. .In this reference exampleThe refractive index adjusting unit 4 is different in that the concave portion 1a has a one-dimensional periodic structure formed in a stripe shape. That is, the difference is that the recesses 1a running in the vertical direction in FIG. 6 (c) are periodically arranged in the horizontal direction in FIG. 6 (c). In additionReference example 1 andSimilar components are denoted by the same reference numerals, and description thereof is omitted.
by the way,Of this reference exampleWhen manufacturing a light emitting element, a pulse laser having a pulse width that does not cause thermal damage to the periphery of the laser irradiation portion in the light emitting element main body A is used in the step of forming the refractive index adjusting unit 4.And Reference Example 1Same butIn Reference Example 1Whereas it is necessary to repeat the process of condensing and irradiating a pulse laser to the substrate 1 of the light emitting element body A for each recess 1a,In this reference exampleIs a refractive index adjusting unit in the light emitting element main body A through the lenses 10 and 10, respectively, as shown in FIG. 7 using a beam splitter (not shown) or a multi-hole mask. 4 is different in that all the recesses 1a are processed at a time by simultaneously irradiating the region to be formed 4 from two directions and causing the irradiation lights to interfere with each other. Here, the beam sizes of the two branched laser beams 9 and 9 are made equal to the size of the processing target surface of the light emitting element main body A. Further, the processing energy density on the surface to be processed of the light emitting element body A is 100 MJ / m as the total processing energy density of the two laser beams 9 and 9.2It is set to be less than about.
ButOf this reference exampleIn the light emitting elementReference example 1 andSimilarly, the provision of the refractive index adjusting unit 4 makes it difficult for multiple reflections in the light emitting element body A to occur, and the light extraction efficiency to the outside is improved.
Also,Of this reference exampleIn the manufacturing method of the light emitting element, the surface processing by the laser can be performed without scanning the laser beam or moving the light emitting element main body A, and the throughput of the forming process of the refractive index adjusting unit 4 is increased. It becomes possible to improve the property.
Note that the method of forming the refractive index adjustment unit 4 is not limited to the method of processing by causing the irradiation lights to interfere with each other as described above, and for example, imaging processing using a phase shift mask may be employed. If the phase shift mask is used, the phase of the laser light transmitted through the adjacent openings is shifted by 180 °, so that the diffracted image generated at the time of fine imaging can be canceled out by the adjacent laser light. It is possible to form a recess having a wide opening width.
Also,Of this reference exampleIn the manufacturing method, the processing target surface of the light emitting element main body A is irradiated with the laser beams 9 and 9 from two directions, but if the processing target surface is irradiated from, for example, four directions, the refractive index adjusting unit 4 is irradiated. It is also possible to form a lattice-shaped recess.
Of this reference exampleBasic structure of light emitting elementAnd Reference Example 1The light-emitting element main body A is substantially the same and has the configuration shown in FIG. 8A, and the structure of the refractive index adjusting unit 4 is different as shown in FIG. 8B. That is,In this reference exampleIn the refractive index adjusting section 4, the shape of the recess 1 a is formed in a V-groove shape in which the opening width is gradually narrowed in the depth direction along the thickness direction of the substrate 1. Here, the maximum opening width of the recess 1aIn Reference Example 1It is the same setting as the opening width of the recess 1a, and the depth dimensionAlso in Reference Example 1It is the same setting as the depth dimension of the recess 1a. Here, the V-groove-shaped recess 1a can be easily processed by making the beam profile of the laser a triangular distribution or a Gaussian distribution. In additionReference example 1 andSimilar components are denoted by the same reference numerals, and description thereof is omitted.
By the way, if the period of the periodic structure of the refractive index adjusting unit 4 is set to a value of about ¼ to 1 times the wavelength of light emitted from the light emitting unit 2, the effective refractive index of the refractive index adjusting unit 4 becomes the substrate 1. Therefore, the total reflection on the other surface side of the substrate 1 hardly occurs, and as a result, multiplexing within the light emitting element body A is performed. Reflection is less likely to occur and the light extraction efficiency to the outside is improved. here,In this reference exampleSince the effective refractive index gradually changes in the thickness direction of the substrate 1, total reflection is further less likely to occur, and as a result, the light extraction efficiency to the outside is improved.
For example, when the emission wavelength of the light emitting unit 2 is 200 to 500 nm, the period of the periodic structure of the refractive index adjusting unit 4 is preferably set to a value of about 1/4 to 4 times the emission wavelength. Here, when the period of the periodic structure is set to a value that is four times the emission wavelength, the light extraction efficiency is improved due to the geometric effect, that is, the wide area of the surface of the substrate 1 and the adoption by scattering. The wave optical effect, that is, by using diffracted light, it is possible to extract reflected light having a total reflection angle or more, and the light extraction efficiency is improved. Further, when the period of the periodic structure is set to a value that is 1/4 to 1 times the emission wavelength, the refractive index of the medium 4b (in this embodiment, the refractive index of the substrate 1) is set to n.2, The refractive index of the medium 4a is n1And the width of the medium 4b in the left-right direction in FIG. 8B is a, the width of the medium 4a is b, and the effective refractive index of the refractive index adjusting unit 4 for TE waves is <n.E>, The effective refractive index <nE> Can be represented by the following formula.
Similarly, the effective refractive index of the refractive index adjusting unit 4 for TM waves is set to <nM>, The effective refractive index <nM> Can be represented by the following formula.
By the way, the refractive index adjusting unit 4 described above has the concave portion 1a formed by condensing and irradiating the laser on the other surface side of the substrate 1 to remove the laser irradiated portion, and the refractive index n of the medium 4b.2Is equal to the refractive index of the sapphire substrate, which is the substrate 1, and the refractive index of the medium 4a is the refractive index n of the medium 4b.1It is a smaller value.
Therefore, as can be seen from the above two formulas, the effective refractive index of the refractive index adjusting unit 4 is an intermediate value between the media on both sides of the refractive index adjusting unit 4 in the thickness direction of the substrate 1. Here, one of the media on both sides of the refractive / separation adjusting unit 4 is sapphire of the substrate 1 and the other is air.
The aboveEmbodiment, each reference example, afterEach implementation describedState and reference examplesHowever, if the period of the periodic structure of the refractive index adjusting unit 4 is set to a value of about 1/4 to 4 times the wavelength of the light emitted from the light emitting unit 2, the change of the refractive index in the light traveling direction can be changed. Thus, multiple reflections within the light emitting element main body A are less likely to occur, and the light extraction efficiency to the outside is improved. Here, if the period of the periodic structure of the refractive index adjusting unit 4 is set to a value of about ¼ to 1 times the wavelength of light emitted by the light emitting unit 2, the effective refractive index of the refractive index adjusting unit 4 is set to the substrate. 1 can be set to an intermediate value between the media on both sides of the refractive index adjusting unit 4 in the thickness direction. For example, in the refractive index adjustment unit 4 in the first embodiment, the medium 4b is a part of the substrate 1 made of a sapphire substrate, and the medium 4a is a modified part of the substrate 1, but the refractive index in the thickness direction of the substrate 1 One of the mediums on both sides of the adjusting unit 4 is sapphire and the other is air, and although the above formula cannot be applied, the effective refractive index is a value between the refractive index of sapphire and the refractive index of air.
Of this reference exampleBasic structure of light emitting elementAnd Reference Example 1The light emitting element main body A having the same configuration as shown in FIG. 9A is provided, and the medium 4b in the refractive index adjusting unit 4 modifies a part of the substrate 1 as shown in FIG. 9B. The difference is that it is formed by quality processing. In additionReference example 1 andSimilar components are denoted by the same reference numerals, and description thereof is omitted.
In this reference exampleTo form the refractive index adjusting portion 4Reference example 1 andSimilarly, for example, the processing energy of a femtosecond laser having a wavelength of 800 nm and a pulse width of 150 fs is set to about 1 μJ / pulse, and the other surface (upper surface in FIG. 9A) of the sapphire substrate is focused and irradiated. By performing removal processing, a recess 1a having an inner diameter of about 100 nm is formed, and then the processing energy of the femtosecond laser is reduced to about 1 μJ / pulse or less, and the portion corresponding to the medium 4b is focused and irradiated to perform modification processing. Thus, a medium 4b having a refractive index different from that of the substrate 1 is formed. However, the composition of the medium 4b does not change from the substrate 1.
by the wayIn Reference Examples 1-4In the step of forming the refractive index adjustment unit 4, the recess 1 a is formed on the other surface side of the substrate 1 by performing a removal process by condensing and irradiating the femtosecond laser on the other surface side of the substrate 1. However, a pulse laser having a pulse width that does not cause thermal damage to the periphery of the laser irradiation portion in the light emitting element main body A is condensed and applied to the other surface side of the substrate 1 to thereby apply the laser irradiation portion (the region where the concave portion 1a is to be formed). Such a process may be employed in which the modified portion is then etched using a solution that can selectively etch the modified portion relative to other portions. Can also prevent thermal damage to the light emitting element body A during the formation of the refractive index adjusting unit 4, and can prevent a decrease in mechanical strength due to the formation of the refractive index adjusting unit 4. Outside without compromising reliability It is possible to provide a light emitting device with improved light extraction efficiency to. For example, 5% hydrofluoric acid may be used as an etchant for selectively etching the modified portion with respect to other portions, and the depth dimension of the recess 1a is set to, for example, 500 nm. Therefore, the etching time when 5% hydrofluoric acid is used as the etching solution may be set to about 5 minutes.
The basic configuration of the light emitting element of the present embodiment is substantially the same as that of the first embodiment, and includes the light emitting element body A having the structure shown in FIG. 10A, and the light emitted from the light emitting unit 2 is shown in FIG. A difference is that the substrate 1 has a reflection portion 20 that reflects toward the other surface (upper surface in FIG. 10A) of the substrate 1 as indicated by arrows in a). Here, as shown in FIGS. 10A and 10B, the reflection unit 20 includes a plurality of fine columnar regions 21 having a refractive index different from that of the substrate 1. They are regularly arranged at a certain interval (for example, an interval of about ½ of the wavelength), and a large number of columnar regions 21 and peripheral portions of the columnar regions 21 constitute a so-called photonic crystal. Further, a refractive index adjusting portion 4 is formed on the other surface side of the substrate 1 as in the first embodiment. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, and description is abbreviate | omitted.
The above-mentioned columnar region 21 has a circular cross section perpendicular to the longitudinal direction, and has a pulse width that does not cause thermal damage to the periphery of the laser irradiation portion in the light emitting element body A, as in the step of forming the refractive index adjusting unit 4. It can be formed by subjecting a laser beam to focused irradiation for modification. That is, the refractive index of the columnar region 21 in the reflecting portion 20 made of photonic crystal is different from the refractive index of the substrate 1, and the refractive index of the peripheral portion 22 of the columnar region 21 is equal to the refractive index of the substrate 1. In the peripheral portion 22 of the columnar region 21, no thermal damage has occurred.
Thus, in the light emitting device of the present embodiment, the light loss due to the light emitted from the light emitting unit 2 being radiated to the outside through the side surface (end surface) of the substrate 1 by providing the reflecting unit 20 in the substrate 1. Since the light emitted from the light emitting unit 2 is guided to the refractive index adjusting unit 4 more efficiently, the light extraction efficiency is improved as a result.
In addition, the reflection part 20 demonstrated in this embodiment is described above.For each reference exampleOf course, it may be provided.
The basic structure of the light emitting device of this embodiment is substantially the same as that of Embodiment 1, and as shown in FIGS. 11 and 12, the area of the light extraction surface on the other surface side of the light emitting device body A is adjusted and light emission is performed. A difference is that a photonic crystal 30 that reflects light from the portion 2 to the light extraction surface side is formed in the substrate 1 made of a sapphire substrate, as indicated by an arrow in FIG.
The photonic crystal 30 has a three-dimensional arrangement in which a large number of fine spherical regions 31 having a refractive index different from that of the substrate 1 are arranged three-dimensionally at intervals of about the wavelength of light (for example, intervals of about ½ of the wavelength). It has a periodic structure, and a large number of spherical regions 31 and a peripheral portion 32 of the spherical region 31 constitute a photonic crystal 30. In the light emitting element main body A, the refractive index adjusting unit 4 similar to that of the first embodiment is formed in a region surrounded by the photonic crystal 30 on the other surface side of the substrate 1. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, and description is abbreviate | omitted.
In the spherical region 31 described above, a pulse laser having a pulse width that does not cause thermal damage to the periphery of the laser irradiation portion in the light emitting element main body A is formed on each of the portions where the spherical regions 31 are to be formed, as in the step of forming the refractive index adjusting unit 4 It is possible to form it by subjecting it to focused irradiation and modifying it. That is, the refractive index of the spherical region 31 in the photonic crystal 30 is different from the refractive index of the substrate 1, and the refractive index of the peripheral portion of the spherical region 31 is equal to the refractive index of the substrate 1. The peripheral portion 32 is not thermally damaged.
Thus, in the light emitting device of the present embodiment, the loss caused by the light emitted from the light emitting unit 2 being radiated to the outside through the side surface (end surface) of the substrate 1 can be reduced and guided to the refractive index adjusting unit 4 more efficiently. As a result, the light extraction efficiency is improved.
In addition, the reflection part 20 demonstrated in this embodiment is each said embodiment.And the above reference examplesOf course, it may be provided.
The basic configuration of the light emitting device of this embodiment is an embodiment.3As shown in FIG. 13, a photonic crystal 30 that reflects light emitted from the light emitting unit 2 toward the light extraction surface side is indicated in the light emitting unit 2 as indicated by an arrow in FIG. 13. It differs in that it is formed. In the present embodiment, a reflection part is configured to reflect the light emitted from the light emitting part 2 by the photonic crystal 30 to the other surface side of the substrate 1.
The photonic crystal 30 has a three-dimensional arrangement in which a large number of fine spherical regions 31 having a refractive index different from that of the substrate 1 are arranged three-dimensionally at intervals of about the wavelength of light (for example, intervals of about ½ of the wavelength). It has a periodic structure, and a large number of spherical regions 31 and a peripheral portion 32 of the spherical region 31 constitute a photonic crystal 30. Here, the number of periods in the three-dimensional periodic structure is desirably four or more. Embodiment3The same components as those in FIG.
In the spherical region 31 described above, a pulse laser having a pulse width that does not cause thermal damage to the periphery of the laser irradiation portion in the light emitting element main body A is formed on each of the portions where the spherical regions 31 are to be formed, as in the step of forming the refractive index adjusting unit 4 It is possible to form it by subjecting it to focused irradiation and modifying it. That is, the refractive index of the spherical region 31 in the photonic crystal 30 is different from the refractive index of GaN, and the refractive index of the peripheral portion of the spherical region 31 is equal to the refractive index of GaN. No thermal damage has occurred in 32. When the constituent material of the light emitting unit 2 is GaN as in the present embodiment, the spherical region 31 is formed when a Ti: sapphire laser having a laser beam wavelength of 800 nm and a pulse width of 150 fs is used as the above-described pulse laser. The processing energy density in the planned area (that is, the processing energy density at the focal point of the laser beam) is 10 to 500 μJ / mm.2If so, the spherical region 31 can be formed without causing thermal damage to the peripheral portion 32.
Thus, in the light emitting device of this embodiment, the amount of light emitted from the light emitting unit 2 and emitted toward the surface side of the p-type GaN layer 2b can be efficiently guided to the refractive index adjusting unit 4. Thus, the extraction efficiency of light extracted through the substrate 1 is improved.
In addition, the reflection part 20 demonstrated in this embodiment is each said embodiment.State and reference examplesOf course, it may be provided.
Of this reference exampleBasic structure of light emitting elementAnd Reference Example 1As shown in FIG. 14, the opening width of each recess 1a in the arrangement direction of the recesses 1a and the width of the medium 4b between the adjacent recesses 1a are adjusted so as to obtain a desired light distribution. Is different. That is,Of this reference exampleThe light emitting element functions as a diffractive optical element such as a binary optical element capable of controlling the light distribution of the light emitted from the refractive index adjusting unit 4. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, and description is abbreviate | omitted.
Of this reference exampleIn the light emitting element, a light distribution in which a straight line passing through the center of the other surface of the substrate 1 and along the thickness direction of the substrate 1 becomes the optical axis M and a light condensing point is formed on the optical axis M is obtained. FIG. 14B adjusts the width of each recess 1a and the width of each medium 4b in the left-right direction. Specifically, the adjacent recesses 1a and the medium 4b are set as one set, and the width of each set (a value obtained by adding the opening width of the recess 1a and the width of the medium 4b) is constant, and the medium 4b becomes closer to the optical axis M. The structure having a larger width is repeated with a period equal to or longer than the emission wavelength of the light emitting section 2. As a result, the diffracted light from the refractive index adjusting unit 4 can be directed to the optical axis M.
ButOf this reference exampleIn the light emitting element, the opening width of each recess 1a and the width of each medium 4b in the arrangement direction of the recesses 1a of the refractive index adjustment unit 4 are adjusted so that a desired light distribution is obtained. Can be obtained.
Of this reference exampleBasic structure of light emitting elementAnd Reference Example 3The difference is that the refractive index adjusting unit 4 is formed on the surface side of the light emitting unit 2 as shown in FIG. That is, the refractive index adjusting unit 4 is formed in a region where the electrode 3 b is not formed on the surface of the p-type GaN layer 2 b constituting the light emitting unit 2. Here, the refractive index adjustment unit 4Reference example 3 andA similar pulse laser is used and is provided within the thickness dimension of the light-emitting element body A. One of the periodic structures of the two types of medium is GaN, and the other medium is air. In additionReference example 3 andSimilar components are denoted by the same reference numerals, and description thereof is omitted.
ButOf this reference exampleAlso in light emitting elementsReference example 3 andSimilarly, the provision of the refractive index adjusting unit 4 makes it difficult for multiple reflections in the light emitting element body A to occur, and the light extraction efficiency to the outside is improved.
Of this reference exampleBasic structure of light emitting elementAnd Reference Example 3As shown in FIG. 16, an electrode 3b formed on the surface of the p-type GaN layer 2b constituting the light emitting section 2 is formed so as to cover the entire surface of the p-type GaN layer 2b. The difference is that the light emitted from the light emitting unit 2 is also used as a reflective film for reflecting the light emitted to the substrate 1 side. In addition,Reference example 3The same components as those in FIG.
ButOf this reference exampleAlso in light emitting elementsReference example 3 andSimilarly, the provision of the refractive index adjusting unit 4 makes it difficult for multiple reflections in the light emitting element body A to occur, and the light extraction efficiency to the outside is improved. Also, In this reference exampleIn the light emitting element, it is possible to prevent light from being emitted from the light emitting unit 2 side in the thickness direction of the light emitting element body A and to radiate most of the emitted light from the substrate 1 side.
Of this reference exampleBasic structure of light emitting elementAnd Reference Example 1As shown in FIG. 17, a surface emitting type in which the light emitting portion 2 made of a semiconductor material is formed on one surface side in the thickness direction of the substrate 1 transparent to the light emitted from the light emitting portion 2. The light-emitting element body A includes a light-emitting element body A having a structure in which the refractive index is changed, which is composed of two types of media having different refractive indexes in a plane along the light extraction surface of the light-emitting element body A. The thickness of the substrate 1 is different from that of the first embodiment. That is,In this reference exampleThe substrate 1 is composed of a set of a plurality of planes, one surface of which is a plane and the other surface is equal to or less than a critical angle with respect to the light beam emitted from the center of the light emitting unit 2. The refractive index adjusting unit 4 similar to that of the first embodiment is formed (that is, the refractive index adjusting unit 4 is formed on each of a plurality of planes constituting the other surface of the substrate 1). here,Of this reference exampleThus, when the cross-sectional shape of the substrate 1 is formed in a trapezoidal shape, an angle between the plane formed by the one surface out of the plurality of planes smaller than 90 ° and an angle formed by the one surface is 90 °. What is necessary is just to set angle (theta) which makes with the virtual plane which becomes in the range of 20-50 degrees.
ButOf this reference exampleIn the light-emitting element, the refractive index adjusting unit 4 having a structure in which the refractive index is changed is formed of two types of media having different refractive indexes in the plane along the light extraction surface of the light-emitting element main body A. As a result, the multiple reflection in the light emitting element main body A hardly occurs, the light extraction efficiency to the outside is improved, and one surface of the substrate 1 is flat and the other surface is the light emitting portion 2. The light beam emitted from the center of the light emitting part 2 is prevented from being totally reflected on the other surface of the substrate 1 by being composed of a set of a plurality of planes having a critical angle or less with respect to the light beam emitted from the center of the substrate. And can efficiently extract light to the outside.
by the way,Of this reference exampleThe substrate 1 in the light emitting element is formed in a shape having a plurality of planes by irradiating the rectangular sapphire substrate with a laser beam 9 from a plurality of directions as shown in FIG. When a Ti: sapphire laser having a laser beam wavelength of 800 nm and a pulse width of 150 fs is used as the above-described pulse laser, the processing energy density for processing the shape of the substrate 1 is 2 J / mm.2That is all. Further, when the refractive index adjusting section 4 is formed on each of the plurality of planes constituting the other surface of the substrate 1, as shown in FIG. 19, the laser beam 9 is focused on the desired plane and removed. The laser beam 9 may be scanned along the other surface of the substrate 1 as indicated by an arrow B in FIG. The other surface side of the substrate 1 for forming the refractive index adjusting portion 4To Reference Example 1The processing energy density at the time of performing the processing for forming the concave portion 1a described above is, for example, 2 to 15 J / mm when a Ti: sapphire laser having a laser beam wavelength of 800 nm and a pulse width of 150 fs is used as the above-described pulse laser.2It may be set within the range. In addition,In this reference exampleIn this embodiment, the recess 1a is formed by performing removal processing on the other surface side of the substrate 1 and the air in the recess 1a is used as the medium 4a. However, by modifying a part of the substrate 1 as in the first embodiment, The medium 4a may be formed.
Of this reference exampleBasic structure of light emitting elementAnd Reference Example 8It is substantially the same, and only the shape of the substrate 1 is different as shown in FIG. In addition,In this reference exampleThe substrate 1 is formed into a plano-convex lens shape in which one surface is a flat surface and the other surface is a part of a spherical surface, and the center of the light emitting portion 2 and the center of the spherical surface are made to coincide. in short,In this reference exampleThe substrate 1 is formed in a hemispherical shape. In additionReference Example 8 andSimilar components are denoted by the same reference numerals, and description thereof is omitted.
ButIn this reference exampleThe shape of the substrate 1 is formed as a plano-convex lens in which one surface is a flat surface and the other surface is a part of a spherical surface, and the center of the light emitting portion 2 and the center of the spherical surface are made to coincide with each other. It is possible to prevent the light flux emitted from the center of the light from being totally reflected on the other surface of the substrate 1 and to efficiently extract light to the outside.
by the way,Of this reference exampleThe substrate 1 in the light emitting element is formed in a hemispherical shape by performing removal processing while scanning the laser beam 9 as shown by an arrow C in FIG. 21 with respect to the sapphire substrate. When a Ti: sapphire laser having a laser beam wavelength of 800 nm and a pulse width of 150 fs is used, the processing energy density for processing the shape of the substrate 1 is 2 J / mm.2That is all. Further, when the refractive index adjusting portion 4 is formed on the other surface of the substrate 1, as shown in FIG. 22, the laser beam 9 is focused on a desired region and removed to perform a removal process. What is necessary is just to scan along the other surface of the board | substrate 1 as shown by the arrow B inside. The other surface side of the substrate 1 for forming the refractive index adjusting portion 4To Reference Example 1The processing energy density at the time of performing the processing for forming the concave portion 1a described above is, for example, 2 to 15 J / mm when a Ti: sapphire laser having a laser beam wavelength of 800 nm and a pulse width of 150 fs is used as the above-described pulse laser.2It may be set within the range. In additionIn this reference exampleIn this embodiment, the recess 1a is formed by performing removal processing on the other surface side of the substrate 1 and the air in the recess 1a is used as the medium 4a. However, by modifying a part of the substrate 1 as in the first embodiment, The medium 4a may be formed.
Of this reference exampleThe basic configuration of the light-emitting element is substantially the same as that of the first embodiment, and as shown in FIG. The surface of the transparent layer 5 has a number of fine irregularities that suppress the occurrence of total reflection of light from the light emitting portion 2 at the interface including the surface (interface between the surface of the transparent layer 5 and air). There is a feature. Here, the transparent layer 5 is provided on the surface of the portion of the light emitting portion 2 where the electrode 3b is not formed. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, and description is abbreviate | omitted.
By the way, as the material of the transparent layer 5, a material whose refractive index is equal to or smaller than the refractive index of the portion (p-type GaN layer 2b) in contact with the light emitting portion 2 may be employed. For example, quartz glass or polycarbonate may be employed. The formation of fine irregularities on the surface of the transparent layer 5 is facilitated. Fine irregularities hereAnd Reference Example 3Similarly, it can be formed by removing a part of the transparent layer 5 using a pulse laser, and it is possible to prevent thermal damage from occurring around the laser irradiated portion. Note that the refractive index of GaN is about 2.0, the refractive index of quartz glass is about 1.46, and the refractive index of polycarbonate is about 1.59. The transparent layer 5 may be formed of a resin that is sealed after the light emitting element body A is mounted.
ButOf this reference exampleIn the light emitting element, total reflection on the surface side of the light emitting section 2 is less likely to occur, and as a result, multiple reflection in the light emitting element body A is less likely to occur, and the light extraction efficiency to the outside is improved. In addition, more light can be extracted from the surface side of the light emitting unit 2, and the light extraction efficiency to the outside can be further improved. Further, there is an advantage that the light extraction efficiency to the outside can be improved without processing the light emitting element body A.
In addition,Of this reference exampleIn the light emitting element, if the light emitting element main body A is provided with the same refractive index adjusting unit 4 as in Embodiment 1 and the transparent layer 5 is laminated on the refractive index adjusting unit 4, the light extraction efficiency to the outside is further improved. Can be made.
Of this reference exampleThe basic configuration of the light emitting element is substantially the same as that of the first embodiment, and as shown in FIG. 24, the other surface (upper surface in FIG. 24) of the sapphire substrate is transparent to the light from the light emitting unit 2. The transparent layer 5 made of a simple material is formed, and a large number of layers that suppress the occurrence of total reflection of light from the light-emitting portion 2 at the interface including the surface on the surface of the transparent layer 5 (interface between the surface of the transparent layer 5 and air) This is characterized in that fine irregularities are formed. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, and description is abbreviate | omitted.
By the way, as the material of the transparent layer 5, a material whose refractive index is equal to or smaller than the refractive index of the substrate 1 may be adopted. For example, if quartz glass or polycarbonate is used, fine irregularities on the surface of the transparent layer 5 are used. Is easy to form. Fine irregularities hereAnd Reference Example 3Similarly, it can be formed by removing a part of the transparent layer 5 using a pulse laser, and it is possible to prevent thermal damage from occurring around the laser irradiated portion. Al2O3Has a refractive index of 1.768, quartz glass has a refractive index of about 1.46, and polycarbonate has a refractive index of about 1.59. The transparent layer 5 may be formed of a resin that is sealed after the light emitting element body A is mounted.
AlsoReference Example 6 andSimilarly, an electrode 3b formed on the surface of the p-type GaN layer 2b constituting the light-emitting portion 2 is formed so as to cover the entire surface of the p-type GaN layer 2b, and the light emitted from the light-emitting portion 2 is formed on the substrate. The difference is that it is also used as a reflective film that reflects to one side.
ButOf this reference exampleIn the light emitting element, multiple reflections within the light emitting element body A are less likely to occur, and the light extraction efficiency to the outside is improved. In addition, light can be prevented from being emitted from the light emitting portion 2 side in the thickness direction of the light emitting element body A, and most of the emitted light can be emitted from the substrate 1 side. Further, there is an advantage that the light extraction efficiency to the outside can be improved without processing the light emitting element body A.
by the way,In this reference exampleIrradiates the surface of the transparent layer 5 by irradiating the surface of the transparent layer 5 with a pulse laser to form fine irregularities, but without irradiating the surface of the transparent layer 5 with the pulse laser, Concavities and convexities may be formed on the surface of the transparent layer 5 by a mold transfer method using a laser, and by adopting a process of forming fine concavities and convexities on the surface of the transparent layer 5 by a mold transfer method using a laser. However, it is possible to prevent the light-emitting element body A from being thermally damaged when the irregularities are formed, and to provide a light-emitting element that improves the efficiency of extracting light to the outside without impairing the reliability. .
Here, in the case where irregularities are formed on the surface of the transparent layer 5 by a mold transfer method using a laser, for example, as shown in FIG. 25, a surface facing the transparent layer 5 is made of a transparent material separately from the transparent layer 5. A mold 40 having fine irregularities is formed on the surface, the surface of the transparent layer 5 is heated by irradiating the surface of the transparent layer 5, and then the mold 40 is pressed against the surface of the transparent layer 5. Fine irregularities can be transferred. Also, it is possible to simultaneously perform the process of heating the surface of the transparent layer 5 by irradiating the surface of the transparent layer 5 through the mold 40 and the process of pressing the mold 40 against the surface of the transparent layer 5. Productivity is improved by performing the two processes simultaneously. As the material of the mold 40, a material having a higher melting point and softening point than the material of the transparent layer 5 may be employed. For example, when quartz glass is employed as the material of the transparent layer 5, for example, sapphire Should be adopted. The laser used in the mold transfer method is preferably an ultrashort pulse laser having a pulse width of 1 ps or less. If a laser having a wavelength that transmits through the mold 40 in a wavelength range from infrared light to ultraviolet light is used, the mold 40 is used. It is possible to adopt a process in which the process of heating the surface of the transparent layer 5 by irradiating the surface of the transparent layer 5 through the laser and the process of pressing the mold 40 against the surface of the transparent layer 5 simultaneously. In addition, when a process of heating the surface of the transparent layer 5 before pressing the mold 40 against the surface of the transparent layer 5 is adopted, the type of laser is not particularly limited as long as the surface of the transparent layer 5 can be heated. For example, a Ti: sapphire laser or an excimer femtosecond laser may be used. For example, when the material of the transparent layer 5 is quartz glass and a Ti: sapphire laser is used as a heating laser, 0.1 to 0.6 J / mm2The transparent layer 5 can be softened with a laser energy density of the order.
Of this reference exampleBasic structure of light emitting elementAnd Reference Example 11Almost the sameIn Reference Example 11The material of the transparent layer 5 is characterized in that a material having a higher refractive index than that of the material in contact with the transparent layer 5 in the light emitting element body A is employed.. In Reference Example 11Since the transparent layer 5 is in contact with the substrate 1 made of a sapphire substrate, the material of the transparent layer 5 may be, for example, GaN, SiC, GaAs, GaP or the like. Here, fine irregularities on the surface of the transparent layer 5And Reference Example 3Similarly, it can be formed by removing a part of the transparent layer 5 using a pulse laser, and it is possible to prevent thermal damage from occurring around the laser irradiated portion. Al2O3Has a refractive index of 1.768, GaN has a refractive index of 2.00, SiC has a refractive index of 3.1 to 4.1, GaAs has a refractive index of 3.3 to 3.8, and GaP has a refractive index of 3. 31. In addition, a large number of fine irregularities are formed on the surface of the transparent layer 5 to suppress the occurrence of total reflection of light from the light emitting portion 2 at the interface including the surface (interface between the surface of the transparent layer 5 and air). pointAnd Reference Example 8The same.
ButOf this reference exampleIn the light-emitting element, reflection at the interface between the light-emitting element body A and the transparent layer 5 is reduced, and the light emitted from the light-emitting portion 2 can be efficiently guided to the transparent layer 5 to improve the light extraction efficiency to the outside. Can be made. Further, there is an advantage that the light extraction efficiency to the outside can be improved without processing the light emitting element body A.
Of this reference exampleBasic structure of light emitting elementAnd Reference Example 1126. As shown in FIG. 26, the difference is that the refractive index adjusting portions 4 and 4 are formed on both surfaces of the substrate 1 in the thickness direction. Here, the refractive index adjusting units 4 and 4And each reference exampleSimilarly, it can be formed by performing processing using a pulse laser. That is, the refractive index adjusting units 4 and 4 can be formed by condensing and irradiating the pulse laser near the interface between the substrate 1 and the transparent layer 5 and near the interface between the substrate 1 and the light emitting unit 2. In additionReference Example 11 andSimilar components are denoted by the same reference numerals, and description thereof is omitted.
ButOf this reference exampleIn the light emitting element, reflection at each of the interface between the substrate 1 and the transparent layer 5 and the interface between the substrate 1 and the light emitting portion 2 can be suppressed, and the light extraction efficiency to the outside can be further improved.
By the way, each of the above embodimentsAnd in each reference example aboveThe refractive index adjusting unit 4 has a periodic structure composed of two types of media having different refractive indexes, but may have a quasi-periodic structure in which a part of the period is shifted or part of the periodicity is eliminated.
According to a first aspect of the present invention, a light emitting portion made of a semiconductor material includes a light emitting element body formed on one surface side in the thickness direction of a substrate transparent to light emitted from the light emitting portion, and from the thickness direction of the substrate. A light-emitting element from which light is extracted, and a refractive index adjusting unit having a structure in which a refractive index is changed, which is composed of two types of media having different refractive indices in a plane parallel to the light-emitting unit, is within the thickness dimension of the light-emitting elementOn the other surface side of the substrate.KeraThe refractive index adjusting unit may be configured such that one of the two types of media is a constituent material of the light emitting element body and the other is a material obtained by modifying the constituent material of the light emitting element body.As a result, multiple reflections within the light emitting element body are less likely to occur, and the light extraction efficiency to the outside is improved.. Further, since the refractive index adjusting unit is formed on the other surface side of the substrate, the light emitted from the light emitting unit is less likely to be totally reflected on the other surface side of the substrate, and the refractive index adjusting unit Since one of the two types of medium is a constituent material of the light emitting element body and the other is a material in which the constituent material of the light emitting element body is modified, the light emitting element body is subjected to a modification process by a laser. Thus, there is an effect that the refractive index adjusting portion can be formed.
According to a second aspect of the present invention, in the first aspect of the invention, the refractive index adjusting unit has a periodic structure or a quasi-periodic structure of two types of media having different refractive indices in a plane parallel to the light emitting unit. The period of the structure or quasi-periodic structure is from 1/4 to the wavelength of the light emitted from the light emitting part.4 timesSince the value is set to a value, the change in the refractive index in the light traveling direction can be reduced, and multiple reflections within the light emitting element body are less likely to occur, and the light extraction efficiency to the outside is improved. .
Claim4The invention of claim1 or claim 2In the invention, since the photonic crystal that adjusts the area of the light extraction surface of the light emitting element body and reflects the light from the light emitting portion toward the light extraction surface is formed in the substrate, from the side surface of the substrate The effect that light can be prevented from being emitted, light can be efficiently guided to the light extraction surface side of the substrate, and light can be efficiently extracted to the outside from a surface parallel to the light emitting portion. There is.
Claim5The invention of claim1 or claim 2In the invention, since the light emitting part has reflection parts regularly arranged at intervals of ½ of the wavelength of the light so as to reflect the light emitted from the light emitting part to the substrate side, the light emitting part It is possible to reflect the light emitted from the substrate to the substrate side, to efficiently guide the light to the other surface side of the substrate, and to efficiently extract the light from the surface parallel to the light emitting portion to the outside. There is an effect.
Claim6The invention of claim 1 to claim 15The method of manufacturing a light-emitting element according to any one of the above, wherein in the step of forming the refractive index adjustment unit, a pulse laser having a pulse width that does not cause thermal damage to the periphery of the laser irradiation portion of the light-emitting element body is condensed. Since the laser-irradiated portion is processed by irradiation, the refractive index adjusting portion can be formed in a non-contact manner without changing the composition, and the light emitting element body is thermally damaged when the refractive index adjusting portion is formed. And a reduction in mechanical strength associated with the formation of the refractive index adjusting portion can be prevented, and a light emitting element that improves the efficiency of extracting light to the outside without impairing reliability is provided. There is an effect that can be.
Claim7The invention of claim 1 to claim 15The method of manufacturing a light-emitting element according to any one of the above, wherein, in the step of forming the refractive index adjusting unit, a pulse laser having a pulse width that does not cause thermal damage to the periphery of the laser irradiation portion in the light-emitting element body emits the light. Since the region where the refractive index adjusting portion is to be formed in the element body is simultaneously irradiated from a plurality of directions and the irradiated light is caused to interfere with each other, the refractive index adjusting portion can be formed in a non-contact manner without a change in composition. In addition, it is possible to prevent thermal damage from occurring in the light emitting element body during the formation of the refractive index adjusting portion, and to prevent a decrease in mechanical strength due to the formation of the refractive index adjusting portion. There is an effect that it is possible to provide a light-emitting element that improves the efficiency of extracting light to the outside without impairing the light. Further, it is possible to collectively form the refractive index adjustment portion,6Productivity can be improved as compared with the invention of the present invention.
Claim8The invention of claim3The method of manufacturing a light emitting device according to claim 1, wherein in the step of forming the reflecting portion, the laser is obtained by condensing and irradiating a pulse laser having a pulse width that does not cause thermal damage to the periphery of the laser irradiation portion in the substrate. Since each of the columnar regions is formed by modifying the irradiated portion, the reflective portion can be easily formed in the substrate in a non-contact manner, and thermal damage occurs with the formation of the reflective portion. There is an effect that can be prevented.
Claim9The invention of claim4The light emitting device manufacturing method according to claim 1, wherein in the step of forming the photonic crystal, the pulse laser having a pulse width that does not cause thermal damage to the periphery of the laser irradiation portion in the substrate is focused and irradiated. Since the laser irradiation portion is modified, the photonic crystal can be easily formed in a non-contact manner in the substrate, and further, it is possible to prevent thermal damage due to the formation of the photonic crystal. There is an effect that can be done.
Claim10The invention of claim5The method of manufacturing a light emitting element according to claim 1, wherein in the step of forming the reflection portion, the laser is obtained by condensing and irradiating a pulse laser having a pulse width that does not cause thermal damage to the periphery of the laser irradiation portion in the light emission portion. Since the irradiated portion is modified, the reflection portion can be easily formed in a non-contact manner in the light emitting portion, and further, it is possible to prevent thermal damage from occurring due to the formation of the reflection portion. There is.
1A and 1B show a first embodiment, in which FIG. 1A is a schematic cross-sectional view, and FIG. 1B is an enlarged view of a main part of FIG.
FIG. 2 is a plan view of the main part of the above.
FIG. 3 is a plan view of a main part of another configuration example same as above.
FIG. 4 is an explanatory diagram of relevant parts of another configuration example of the above.
[Figure 5]Reference Example 1(A) is a schematic sectional drawing, (b) is the principal part enlarged view of (a).
[Fig. 6]Reference example 2(A) is a schematic sectional view, (b) is an enlarged view of the main part of (a), and (c) is a plan view of the main part.
FIG. 7 is an explanatory diagram of the manufacturing method of the above.
[Fig. 8]Reference Example 3(A) is a schematic sectional drawing, (b) is the principal part enlarged view of (a).
FIG. 9Reference Example 4(A) is a schematic sectional drawing, (b) is the principal part enlarged view of (a).
FIG. 10 is an embodiment.2(A) is a schematic sectional view, (b) is a schematic plan view.
FIG. 11 Embodiment3It is a schematic sectional drawing which shows.
12A is a cross-sectional view taken along line C-C ′ of FIG. 11, FIG. 12B is a cross-sectional view taken along line D-D ′ of FIG. 11, and FIG. 12C is a cross-sectional view taken along line E-E ′ of FIG.
FIG. 13 is an embodiment.4It is a schematic sectional drawing which shows.
FIG. 14Reference Example 5(A) is a principal part top view, (b) is a principal part sectional drawing.
FIG. 15Reference Example 6It is a schematic sectional drawing shown.
FIG. 16Reference Example 7It is a schematic sectional drawing shown.
FIG. 17Reference Example 8It is a schematic sectional drawing shown.
FIG. 18 is an explanatory diagram of the manufacturing method of the above.
FIG. 19 is an explanatory diagram of the manufacturing method of the above.
FIG. 20Reference Example 9It is a schematic sectional drawing shown.
FIG. 21 is an explanatory diagram of the manufacturing method of the same.
FIG. 22 is an explanatory diagram of the manufacturing method of the same.
FIG. 23Reference Example 10It is a schematic sectional drawing shown.
FIG. 24Reference Example 11It is a schematic sectional drawing shown.
FIG. 25 is an explanatory diagram of an example of the manufacturing method.
FIG. 26Reference Example 13It is a schematic sectional drawing shown.
FIG. 27 is a schematic sectional view showing a conventional example.
2 Light emitting part
2a n-type GaN layer
2b p-type GaN layer
3a, 3b electrode
4 Refractive index adjuster
4a Medium
4b Medium
A Light-emitting element body
A light emitting device in which a light emitting portion made of a semiconductor material has a light emitting device body formed on one surface side in the thickness direction of a substrate transparent to light emitted from the light emitting portion, and light is extracted from the thickness direction of the substrate. And a refractive index adjusting unit having a structure in which the refractive index is changed, which is composed of two types of media having different refractive indexes in a plane parallel to the light emitting unit, is provided on the other surface side of the substrate within the thickness dimension of the light emitting element body. The light-emitting element is provided, wherein one of the two kinds of media is a constituent material of the light-emitting element body, and the other is a material obtained by modifying the constituent material of the light-emitting element body. .
The refractive index adjusting unit has a periodic structure or a quasi-periodic structure of two types of media having different refractive indexes in a plane parallel to the light emitting unit, and the period of the periodic structure or quasiperiodic structure emits light at the light emitting unit. 2. The light emitting device according to claim 1, wherein the light emitting device is set to a value of 1/4 to 4 times the wavelength of light.
A number of minute columnar regions having different refractive indexes from the substrate are regularly spaced by the wavelength of the light with the thickness direction as a longitudinal direction so that the light emitted from the light emitting portion is reflected to the other surface side of the substrate. emitting element mounting serial to claim 1 or claim 2, characterized that you have to array of the reflective portion in the substrate.
Claim 1 or, characterized that you photonic crystal that reflects the light extraction surface side light from the light emitting element by adjusting the area of the light extraction surface of the main body and the light emitting portion is formed in the substrate serial mounting of the light emitting device in claim 2.
Claims, characterized that you have a reflecting portion which are regularly arranged at half the interval of the wavelength of to reflect light emitted by said light emitting portion to the substrate side to the light emitting portion serial mounting of the light emitting element 1 or claim 2.
6. The method of manufacturing a light-emitting element according to claim 1, wherein in the step of forming the refractive index adjusting unit, a pulse that does not cause thermal damage to the periphery of the laser irradiation portion in the light-emitting element body. A method for manufacturing a light-emitting element, characterized in that a laser irradiation portion is processed by condensing and irradiating a pulse laser having a width.
The method for manufacturing a light emitting device according to any one of claims 1 to 5, in the step of forming the refractive index adjusting unit, does not cause heat damage to the laser irradiated portion surrounding in the light-emitting element body pulse method of fabricating a light emitting device which is characterized in that pressurized Engineering by interfere with each other by irradiating the irradiation light between simultaneously from multiple directions pulsed laser forming region of the refractive index adjusting unit in the light-emitting element body width.
A method according to claim 3 Symbol mounting of the light emitting element, in the step of forming the reflective portion, condensing a pulsed laser having a pulse width which does not cause the occurrence of thermal damage to record over The irradiated portion near to said substrate method of manufacturing a light-emitting device characterized by that form each of said columnar regions by modifying the laser irradiated portion irradiated with light.
The method for manufacturing a light emitting device according to claim 4, before SL in the step of forming a photonic crystal, condensing a pulsed laser having a pulse width in the substrate does not cause the occurrence of thermal damage to the laser irradiated portion around method of manufacturing a light-emitting element irradiating the features and reforming child the laser irradiated portion.
The method for manufacturing a light emitting device according to claim 5, before SL in the step of forming the reflecting portion, the light emitting portion of the laser irradiated part condensing a pulsed laser having a pulse width which does not cause the occurrence of thermal damage irradiation of the surrounding Then, the method of manufacturing a light emitting element, wherein the laser irradiation portion is modified .
JP2003086107A 2002-07-29 2003-03-26 Light emitting element and manufacturing method thereof Active JP4329374B2 (en)
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JP2003086107A Active JP4329374B2 (en) 2002-07-29 2003-03-26 Light emitting element and manufacturing method thereof
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