Abstract:
It is an object of the present invention to provide a new light-emitting element and manufacturing method thereof in which actively diffusing a material into a film formation layer is utilized where an interface state and interdiffusion between a compound semiconductor substrate and a film formation layer formed thereover are not considered to be problematic. According to one feature of the present invention, unevenness is formed over the surface of a compound semiconductor substrate through chemical treatment, a compound semiconductor layer is formed over the surface of the compound semiconductor substrate having unevenness, atoms of the compound semiconductor substrate are diffused into the compound semiconductor layer through heat treatment, a first conductive layer is formed over the compound semiconductor substrate, and a second conductive layer is formed over the compound semiconductor layer.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a light-emitting element and manufacturing method thereof. More specifically, the present invention relates to a light-emitting element in which a compound semiconductor layer functioning as a light-emitting layer is formed over a compound semiconductor substrate and a manufacturing method thereof.  
         [0003]     2. Description of the Related Art  
         [0004]     Recently, elements such as light-emitting diodes, photodiodes, photovoltaic cells, semiconductor lasers, high-speed transistors, and the like, in which, formed over a compound semiconductor substrate is a compound semiconductor of a different kind, have been used extensively. In addition, a good crystal can be obtained through use of a compound semiconductor substrate in an EL device which is driven by application of a high electric field, and a thin film inorganic EL device with high luminance can be obtained, as well.  
         [0005]     However, when a compound semiconductor layer is formed over a compound semiconductor substrate, because an interface state is formed and interdiffusion is generated in the vicinity of a semiconductor interface by a thermal process due to differences in the lattice parameters and coefficients of thermal expansion, an injected carrier is trapped in the interface so that it is difficult to obtain good crystallinity. Consequently, obtaining good crystallinity in a simple layered structure is incredibly difficult to attain.  
         [0006]     In order to solve these problems, research has been conducted in which, for example, a moderation (buffer) layer is used between a compound semiconductor substrate that contains an element belonging to group 13 of the periodic table and an element belonging to group 15 of the periodic table and a compound semiconductor layer that contains an element belonging to group 12 of the periodic table and an element belonging to group 16 of the periodic table formed over the compound semiconductor substrate, an anneal process is performed after film formation, and the like.  
         [0007]     Furthermore, a manufacturing process has been examined in which reduction of interface states, low costs, and simplicity in production through formation of a porous semiconductor layer over a compound semiconductor substrate or use of a layer of an organic material as a buffer layer is considered. (For examples, see to Patent Document 1: Japanese Published Patent Application No. 2001-156321 and Patent Document 2: Japanese Published Patent Application No. 2003-86508.)  
       SUMMARY OF THE INVENTION  
       [0008]     However, it is an object of the present invention to provide a new light-emitting element which actively uses diffusion into a film formation layer and a manufacturing method thereof, in which influences by interface states and interdiffusion between a compound semiconductor substrate and a film formation layer formed thereover are not considered to be problematic. In addition, it is an object of the present invention to offer a light-emitting element in which, compared to traditional light-emitting elements, resistance has been lowered and luminance is high and a manufacturing method thereof.  
         [0009]     A light-emitting element of the present invention is characterized by having a first conductive layer and a compound semiconductor layer formed over a compound semiconductor substrate and a second conductive layer formed over the compound semiconductor layer, where an element, the same element as that included in the compound semiconductor substrate, is contained in the compound semiconductor layer. In addition, as for the element contained in the compound semiconductor layer, after a compound semiconductor layer used to function as a light-emitting layer is formed over the compound semiconductor substrate, the element contained in the compound semiconductor substrate is diffused into the compound semiconductor layer by heat treatment or the like.  
         [0010]     A light-emitting element of the present invention is characterized by having a first conductive layer and a compound semiconductor layer formed over a compound semiconductor substrate, a dielectric layer formed over the compound semiconductor layer, and a second conductive layer formed over the dielectric layer, where an element contained in the compound semiconductor layer is the same element as that contained in the compound semiconductor substrate.  
         [0011]     In the above structure, the compound semiconductor layer is characterized by having a host material that is a compound that contains an element belonging to group 2 or group 12 of the periodic table and an element belonging to group 16 of the periodic table and an impurity element with a luminescent center.  
         [0012]     In addition, the compound semiconductor layer can be formed as a plurality of stacked layers.  
         [0013]     A manufacturing method of the present invention includes the following steps: forming a compound semiconductor layer over a compound semiconductor substrate; making an element contained in the compound semiconductor layer be diffused into the compound semiconductor substrate by heat treatment or the like; forming a first conductive layer over the compound semiconductor substrate; and forming a second conductive layer over the compound semiconductor layer.  
         [0014]     A manufacturing method of the present invention includes the following steps: forming unevenness on the surface of the compound semiconductor substrate by chemical treatment; forming a compound semiconductor layer over the surface of the compound semiconductor substrate having unevenness; making an element contained in the compound semiconductor layer be diffused into the compound semiconductor substrate; forming a first conductive layer over the compound semiconductor substrate; and forming a second conductive layer over the compound semiconductor layer.  
         [0015]     In addition, the manufacturing method of the present invention is characterized as one in which a dielectric layer is formed between the compound semiconductor layer and the second conductive layer of the above structure.  
         [0016]     In addition, the manufacturing method of the present invention is characterized as one in which a layer that contains the impurity element with a luminescent center and the host material that is a compound containing an element belonging to group 2 or group 12 of the periodic table and an element belonging to group 16 of the periodic table is used as the compound semiconductor layer in the structure described above.  
         [0017]     In addition, the manufacturing method of the present invention is characterized as one in which the compound semiconductor layer of the above structure can be formed as a plurality of stacked layers.  
         [0018]     Through diffusion of the element of the compound semiconductor substrate into a film formation layer formed over the compound semiconductor substrate, a new energy level is formed in the film formation layer and the rate of movement of carriers to the film formation layer can be improved. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]      FIGS. 1A  to  1 D are diagrams used to illustrate an example of the light-emitting element of the present invention.  
         [0020]      FIGS. 2A  to  2 C are diagrams used to illustrate an example of the light-emitting element of the present invention.  
         [0021]      FIGS. 3A  to  3 D are diagrams used to illustrate an example of the light-emitting element of the present invention.  
         [0022]      FIGS. 4A and 4B  are diagrams used to illustrate an example of a light-emitting device that uses the light-emitting element of the present invention.  
         [0023]      FIG. 5  is a diagram used to illustrate an example of an application configuration of a light-emitting device that uses the light-emitting element of the present invention.  
         [0024]      FIGS. 6A and 6B  are diagrams used to illustrate an example of a light-emitting device that uses the light-emitting element of the present invention.  
         [0025]      FIGS. 7A  to  7 D are diagrams used to illustrate an example of an application configuration of a light-emitting device that uses the light-emitting element of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0026]     Embodiment Modes of the present invention will be explained below with reference to the accompanying drawings. However, the present invention is not limited to the following explanation, and it is to be easily understood that various changes and modifications will be apparent to those skilled in the art. Therefore, unless such changes and modifications depart from the scope of the invention, they should be construed as being included therein. Note that identical portions or portions that have the same function in all figures used for explaining embodiment modes are denoted by the same reference numerals and detailed descriptions thereof are omitted.  
       Embodiment Mode 1  
       [0027]     In this embodiment mode, one example of a light-emitting element and manufacturing method thereof of the present invention will be described with reference to drawings.  
         [0028]     The light-emitting element shown in this embodiment mode has a compound semiconductor layer  102  formed over a compound semiconductor substrate  101 , a first conductive layer  103  that is electrically connected to the compound semiconductor substrate  101 , and a second conductive layer  104  that is electrically connected to the compound semiconductor layer  102 . Here, an example is shown in which the first conductive layer  103  is formed over the compound semiconductor substrate  101  and the second conductive layer  104  is formed over the compound semiconductor layer  102 .  
         [0029]     First, a compound semiconductor substrate  101  is prepared ( FIG. 1A ). GaAs, GaP, InP, or the like, for example, can be used for the compound semiconductor substrate  101 . Furthermore, a p-type compound semiconductor may be used as a substrate. It is to be noted that a treated layer may be formed over the surface of the compound semiconductor substrate  101  in advance through performance of chemical treatment or the like.  
         [0030]     When a p-type GaAs substrate is used for the compound semiconductor substrate  101 , for example, a treated layer having an uneven surface can be formed over the surface through performance of chemical treatment with a mixture of sulfuric acid, a hydrogen peroxide solution, and water. The volume ratio of the mixture of sulfuric acid, the hydrogen peroxide solution, and water at this time is from 3:1:1 to 8:1:1, preferably from 3:1:1 to 4:1:1. Furthermore, the chemical treatment temperature is from 20° C. to 80° C.; preferably, the chemical treatment is performed under the condition of a temperature from 70° C. to 80° C.  
         [0031]     In addition to the mixture described above being used for chemical treatment of the GaAs substrate, a mixture of ammonium hydroxide and a hydrogen peroxide solution, a mixture of orthophosphoric acid and a hydrogen peroxide solution, aqueous sodium hydroxide, a mixture of aqueous citric acid and ethanol, a mixture of bromine and ethanol, or the like may be used for performing chemical treatment of the GaAs substrate.  
         [0032]     In addition, when GaP or InP is used for the compound semiconductor substrate  101 , chemical treatment may be performed using a mixture of bromine and ethanol, hydrochloric acid, a mixture of hydrochloric acid and orthophosphoric acid, a mixture of hydrochloric acid and sulfuric acid, or the like.  
         [0033]     Here, an example is shown in which a p-type GaAs substrate is used for the compound semiconductor substrate  101  and a treated layer  105  having an uneven surface is formed over the surface of the compound semiconductor substrate  101  through performance of chemical treatment of the GaAs substrate. Also, the treated layer  105  having the uneven surface may be formed by other than the above methods.  
         [0034]     Next, a compound semiconductor layer  102  that is to become a light-emitting material is formed over the surface of the compound semiconductor substrate  101  by use of an electron beam evaporation technique ( FIG. 1B ). The deposition rate with the electron beam evaporation technique is from 0.1 nm/s to 20 nm/s; preferably, electron beam evaporation is performed at a deposition rate of from 0.5 nm/s to 2 nm/s. In addition, the compound semiconductor layer  102  is formed so as to have a thickness of from 100 nm to 2000 nm; preferably, the compound semiconductor layer  102  is formed so as to have a thickness of from 300 nm to 1000 nm. Substrate temperature during deposition is from 150° C. to 300° C.; preferably, the substrate temperature is set to be from 200° C. to 250° C.  
         [0035]     Furthermore, in addition to being formed through use of the electron beam evaporation technique, the compound semiconductor layer  102  may be formed through use of a resistive heating method, a sputtering method, a CVD method, a molecular beam evaporation (MBE) method, or the like.  
         [0036]     The compound semiconductor layer  102  can be formed of a host material that is a compound containing an element belonging to group 2 or group 12 of the periodic table and an element belonging to group 16 of the periodic table; a compound containing an element belonging to group 13 of the periodic table and an element belonging to group 15 of the periodic table; or a compound containing an element belonging to group 2 of the periodic table, an element belonging to group 13 of the periodic table, and an element belonging to group 16 of the periodic table; and an impurity element with a luminescent center.  
         [0037]     For the host material, any of the following can be used. Zinc sulfide (ZnS), calcium sulfide (CaS), strontium sulfide (SrS), zinc oxide (ZnO), or the like can be used as the compound containing an element belonging to group 2 or group 12 of the periodic table and an element belonging to group 16 of the periodic table. Gallium nitride (GaN), aluminum nitride (AlN), or the like can be used as the compound containing an element belonging to group 13 of the periodic table and an element belonging to group 15 of the periodic table. Barium thioaluminate (BaAl 2 S 4 ), calcium thiogallate (CaGa 2 S 4 ), or the like can be used as the compound containing an element belonging to group 2 of the periodic table, an element belonging to group 13 of the periodic table, and an element belonging to group 16 of the periodic table.  
         [0038]     For the impurity element, at least one of any of the following is included: manganese (Mn), europium (Eu), samarium (Sm), terbium (Tb), praseodymium (Pr), thulium (Tm), cerium (Ce), copper (Cu), silver (Ag), chlorine (Cl), and fluorine (F). It is to be noted that the molecular concentration of the impurity element with respect to the molecular concentration of the host material is from 0.1 mol % to 20 mol %; preferably, the molecular concentration is set to be from 0.5 mol % to 10 mol %.  
         [0039]     In addition, the compound semiconductor layer  102  may be doped with an element belonging to group 11 of the periodic table (for example, copper (Cu), silver (Ag), or the like), an element belonging to group 13 or group 15 of the periodic table (for example, aluminum (Al), gallium (Ga), indium (In), nitrogen (N), phosphorus (P), arsenic (As), antimony (Sb), or the like), or an element belonging to group 14 of the periodic table (for example, carbon (C), silicon (Si), germanium (Ge), or the like), in advance, through a solid phase reaction or the like. Through doping of the compound semiconductor layer  102  with one or more of these elements, a change in the crystal system can be induced. It is to be noted that the molecular concentration of the dopant material is set to be from 0.1 mol % to 50 mol % with respect to the molecular concentration of the compound semiconductor layer  102 ; preferably, the molecular concentration of the dopant material is set to be from 0.5 mol % to 10 mol %.  
         [0040]     After the compound semiconductor layer  102  is formed, heat treatment is performed ( FIG. 1C ). Here, annealing is performed using an oven, an electric furnace, or a quartz tube under an atmosphere containing nitrogen (N 2 ) and argon (Ar) at a temperature of from 550° C. to 800° C., preferably, from 600° C. to 700° C. The annealing is performed for a length of time of from 30 minutes to 12 hours, preferably, a length of time of from 1 hour to 4 hours. It is to be noted that, in addition to being performed through an annealing method, heat treatment may be performed through irradiation with a laser beam.  
         [0041]     Through heat treatment, the element of the compound semiconductor substrate  101  is diffused from the compound semiconductor substrate  101  into a film formation layer (here, the compound semiconductor layer  102 ). As a result, a new energy level is formed in the compound semiconductor layer  102 . Accordingly, the injection of carriers from the compound semiconductor substrate  101  into the compound semiconductor layer  102  is improved, and the probability for energy transfer to the new energy level formed in the compound semiconductor layer  102  is increased and luminous efficiency is improved. In addition, in this case, because adhesiveness improves through formation of the treated layer  105  over the compound semiconductor substrate  101 , diffusion from the compound semiconductor substrate  101  into the compound semiconductor layer  102  occurs more noticeably, and more energy levels can be formed.  
         [0042]     Generally, due to an auto-compensation effect, it is difficult to form a p-type compound semiconductor layer with low resistance from a compound semiconductor (for example, a compound semiconductor of ZnS, CaS, or SrS) containing an element belonging to group 2 or group 12 of the periodic table and an element belonging to group 16 of the periodic table. However, in the present invention, through active diffusion of the element of the compound semiconductor substrate (for example, a GaAs substrate) from a p-type compound semiconductor substrate into a compound semiconductor layer and formation of a new energy level, the resistance of a compound semiconductor layer containing an element belonging to group 2 or group 12 of the periodic table and an element belonging to group 16 of the periodic table can be lowered, and the rate of movement of carriers can be improved.  
         [0043]     In addition, when a compound containing an element belonging to group 13 of the periodic table and an element belonging to group 15 of the periodic table (for example, GaAs, GaN, GaP, InP, or AlGaN) or a compound containing an element belonging to group 2 of the periodic table, an element belonging to group 13 of the periodic table, and an element belonging to group 16 of the periodic table (for example, BaAl 2 S 4 , CaGa 2 S 4 , or SrGa 2 S 4 ) is formed over the compound semiconductor substrate  101 , there are many defect levels due to a difference in lattice constants between the compound semiconductor substrate  101  and the compound semiconductor layer  102 ; however, with the treated layer  105  functioning as an intermediate layer between the compound semiconductor substrate  101  and the compound semiconductor layer  102 , a compound semiconductor layer  102  in which defect levels have been reduced can be formed.  
         [0044]     Next, a first conductive layer  103  that is electrically connected to the compound semiconductor substrate  101  and a second conductive layer  104  that is electrically connected to the compound semiconductor layer  102  are formed ( FIG. 1D ). Here, the first conductive layer  103  is formed over the compound semiconductor substrate  101 , and the second conductive layer  104  is formed over the compound semiconductor layer  102 .  
         [0045]     The first conductive layer  103  can be formed of aluminum (Al), gold (Au), or the like at a thickness of from 100 nm to 500 nm by an electron beam evaporation technique, a resistive heating method, a sputtering method, a CVD method, an MBE method, or the like.  
         [0046]     The second conductive layer  104  can be formed of a conductive material with a light-transmitting property by an electron beam evaporation technique, a resistive heating method, a sputtering method, a CVD method, an MBE method, or the like, so as to have a thickness of from 100 nm to 500 nm. The conductive material with a light-transmitting property may be formed of, for example, indium tin oxide (ITO), indium tin oxide containing silicon or silicon oxide, indium zinc oxide (IZO), indium tin oxide containing tungsten oxide and zinc oxide (IWZO), or the like.  
         [0047]     A light-emitting element can be formed through performance of the above steps. The light-emitting element shown in  FIG. 1  can be the type of light-emitting element that is driven by direct current. In this case, the first conductive layer  103  is used as an anode, and the second conductive layer  104  is used as a cathode.  
       Embodiment Mode 2  
       [0048]     In this embodiment mode, a light-emitting element whose structure differs from that of the above embodiment mode will be explained with reference to drawings.  
         [0049]     The light-emitting element shown in the present embodiment mode is one which has a first compound semiconductor layer  102  formed over a compound semiconductor substrate  101 , a second compound semiconductor layer  106  formed over the first compound semiconductor layer  102 , a first conductive layer  103  that is electrically connected to the compound semiconductor substrate  101 , and a second conductive layer  104  that is electrically connected to the second compound semiconductor layer  106  ( FIG. 2A ). The structure shown in  FIG. 1D  has become a structure in which the second compound semiconductor layer  106  is formed between the compound semiconductor layer  102  and the second conductive layer  104 . Furthermore, the compound semiconductor layer may be formed as a stacked layer of three or more layers.  
         [0050]     A compound of an element belonging to group 1 of the periodic table, an element belonging to group 13 of the periodic table, and an element belonging to group 16 of the periodic table (for example, a compound such as CuAlS 2 , CuGaS 2 , CuInS 2 , AgAlS 2 , AgGaS 2 , AgInS 2 , or the like) or a chalcopyrite compound of an element belonging to group 12 of the periodic table, an element belonging to group 14 of the periodic table, and an element belonging to group 15 of the periodic table (for example, a compound such as ZnSiP 2 , ZnGeP 2 , or the like) can be used for the second compound semiconductor layer  106 .  
         [0051]     In addition, the second compound semiconductor layer  106  may be doped with an element belonging to group 11 of the periodic table (for example, copper (Cu), silver (Ag), or the like), an element belonging to group 13 or group 15 of the periodic table (for example, aluminum (Al), gallium (Ga), indium (In), nitrogen (N), phosphorous (P), arsenic (As), antimony (Sb), or the like), or an element belonging to group 14 of the periodic table (for example, carbon (C), silicon (Si), germanium (Ge), or the like), in advance, through a solid phase reaction. Through doping of the compound semiconductor layer  102  with one or more of these elements, a change in the crystal system can be induced. It is to be noted that the molecular concentration of the dopant material is set to be from 0.1 mol % to 50 mol % with respect to the molecular concentration of the compound semiconductor layer  106 ; preferably, the molecular concentration is set to be from 0.5 mol % to 10 mol %.  
         [0052]     It is to be noted that the compound semiconductor substrate  101 , the first compound semiconductor layer  102 , the first conductive layer  103 , and the second conductive layer  104  can be formed using the materials and manufacturing methods shown in the above embodiment mode.  
         [0053]     In addition, in the structure shown in  FIG. 2A , heat treatment is performed after the first compound semiconductor layer  102  and the second compound semiconductor layer  106  are formed and stacked over the compound semiconductor substrate  101 . Consequently, the element of the compound semiconductor substrate  101  is diffused from the compound semiconductor substrate  101  into a film formation layer (here, either one of the first compound semiconductor layer  102  or second compound semiconductor layer  106  or both of them). As a result, a new energy level is formed in the first compound semiconductor layer  102  and the second compound semiconductor layer  106 . Accordingly, the injection of carriers from the compound semiconductor substrate  101  into the film formation layer is improved, and the probability for energy transfer to the new energy level formed in the film formation layer is increased and luminous efficiency is improved.  
         [0054]     Furthermore, in addition to the structure shown in  FIG. 2A , it is possible to set the structure as one in which a second compound semiconductor layer  106  is formed over a compound semiconductor substrate  101  and a first compound semiconductor layer  102  is formed thereover ( FIG. 2B ). In this case, a second conductive layer  104  is formed over the first compound semiconductor layer  102 .  
         [0055]     In addition, it is possible to set the structure as one in which a first compound semiconductor layer  102  is not formed, but a second compound semiconductor layer  106  is formed over a compound semiconductor substrate  101  and a second conductive layer  104  is formed over the second compound semiconductor layer  106  ( FIG. 2C ).  
         [0056]     A light-emitting element can be formed through performance of the above-mentioned steps. The light-emitting element shown in  FIGS. 2A  to  2 C can be the type of light-emitting element that is driven by direct current. In this case, the first conductive layer  103  is used as an anode, and the second conductive layer  104  is used as a cathode.  
         [0057]     The present embodiment mode can be freely combined with the above embodiment mode.  
       Embodiment Mode 3  
       [0058]     In this embodiment mode, a light-emitting element whose structure differs from that of the above embodiment modes will be explained with reference to drawings.  
         [0059]     The light-emitting element shown in the present embodiment mode is one which has a compound semiconductor layer  102  formed over a compound semiconductor substrate  101 , a dielectric layer  110  formed over the compound semiconductor layer  102 , a first conductive layer  103  that is electrically connected to the compound semiconductor substrate  101 , and a second conductive layer  104  that is electrically connected to the dielectric layer  110  ( FIG. 3A ). The structure shown in  FIG. 1C  has become a structure in which the dielectric layer  110  is formed between the compound semiconductor layer  102  and the second conductive layer  104 .  
         [0060]     The dielectric layer  110  is formed as a single-layer or multilayer structure of BaTiO 3 , SrTiO 3 , Ta 2 O 5 , Si 3 N 4 , SiO 2 , Al 2 O 3 , Y 2 O 3 , or the like at a thickness of from 300 to 1000 nm by an electron beam evaporation method, a resistive heating method, a sputtering method, a CVD method, an MBE method, or the like.  
         [0061]     With the dielectric layer  110  being formed between the compound semiconductor layer  102  and the second conductive layer  104 , driving by alternating current becomes possible.  
         [0062]     Furthermore, in addition to the structure shown in  FIG. 2A , the structure may be set as one in which a dielectric layer  110  is formed between a second compound semiconductor layer  106  and a second conductive layer  104  ( FIG. 3B ); in addition to the structure shown in  FIG. 2B , the structure may be set as one in which a dielectric layer  110  is formed between a first compound semiconductor layer  102  and a second conductive layer  104  ( FIG. 3C ); in addition to the structure shown in  FIG. 2C , the structure may be set as one in which a dielectric layer  110  is formed between a second compound semiconductor layer  106  and a second conductive layer  104  ( FIG. 3D ).  
         [0063]     The light-emitting element shown in  FIG. 3  can be the type of light-emitting element that is driven by alternating current.  
         [0064]     The present embodiment mode can be freely combined with the above embodiment modes.  
       Embodiment Mode 4  
       [0065]     In the present embodiment mode, a light-emitting device that includes a light-emitting element of the present invention will be described with reference to  FIGS. 4A and 4B . It is to be noted that  FIG. 4A  shows a top view and  FIG. 4B  shows a cross-sectional view of a cross-section taken along the line A-B in  FIG. 4A .  
         [0066]     In  FIGS. 4A and 4B , a first conductive layer  203  and a compound semiconductor layer  202  are formed over a compound semiconductor substrate  201 . In addition, a second conductive layer  204  is formed over the compound semiconductor layer  202 . It is to be noted that, for the compound semiconductor substrate  201 , the compound semiconductor layer  202 , the first conductive layer  203 , and the second conductive layer  204 , those described in the above embodiment modes can be used.  
         [0067]     The compound semiconductor layer  202  is surrounded by the first conductive layer  203 . A light-emitting device that includes the light-emitting element shown in  FIGS. 4A and 4B  can be driven by direct current. It is to be noted that, as described in the above embodiment modes, forming a dielectric layer between the compound semiconductor layer  202  and the second conductive layer  204  and driving the light-emitting device that includes the light-emitting element shown in  FIGS. 4A and 4B  by alternating current may be done, as well. In addition, the compound semiconductor layer  202  may be formed as a stacked layer.  
         [0068]     Next, an example of an application mode of the light-emitting device shown in the present embodiment mode is shown in  FIG. 5 .  
         [0069]     In  FIG. 5 , an example is shown in which a light-emitting device employing the light-emitting element of the present embodiment mode is used as the lighting unit of a desk lamp. The desk lamp shown in  FIG. 5  has a case  2001  and a light source  2002 , where a light-emitting device of the present invention is used as the light source  2002 . Because the light-emitting device of the present invention is one in which emission of light at high luminance is possible, when detailed work is being performed, the area at hand where the work is being performed can be brightly lighted up.  
         [0070]     The present embodiment mode can be freely combined with the above embodiment modes.  
       Embodiment Mode 5  
       [0071]     In the present embodiment mode, a light-emitting device differing from that of Embodiment Mode 4 will be described with reference to  FIGS. 6A and 6B . It is to be noted that  FIG. 6A  shows a top view and  FIG. 6B  shows a cross-sectional view of a cross-section taken along the line A-B in  FIG. 6A .  
         [0072]     The light-emitting device shown in the present embodiment mode is a light-emitting device in which driving of a light-emitting element can be performed without formation of an element, such as a transistor or the like, used for driving.  
         [0073]     In  FIGS. 6A and 6B , a compound semiconductor layer  212  and a first conductive layer  213  are formed over a compound semiconductor substrate  211 . In addition, an insulating film  218  is formed so as to cover an edge of the compound semiconductor layer  212  and the first conductive layer  213 , and a second conductive layer  214  is formed as selected so as to cover the insulating layer  218 . The second conductive layer  214  is formed so as to be in contact with an upper surface of the compound semiconductor layer  212 . In addition, the first conductive layer  213  is formed so as to surround the compound semiconductor layer  212 . It is to be noted that, for the compound semiconductor substrate  211 , the compound semiconductor layer  212 , the first conductive layer  213 , and the second conductive layer  214 , those described in the above embodiment modes can be used.  
         [0074]     Here, a 3-pixel by 3-pixel light-emitting element is shown. The first conductive layer  213  is formed so that the pixels are electrically connected in a first direction (in a the pixels are electrically connected in a second direction (in a horizontal direction in the drawing).  
         [0075]     A light-emitting device that includes the light-emitting element shown in  FIGS. 6A and 6B  can be driven by direct current. It is to be noted that, as described in the above embodiment modes, forming a dielectric layer between the compound semiconductor layer  212  and the second conductive layer  214  and driving the light-emitting device that includes the light-emitting element shown in  FIGS. 6A and 6B  by alternating current may be done, as well. In addition, the compound semiconductor layer  212  may be formed as a stacked layer.  
         [0076]     Next, examples of application modes of the light-emitting device shown in this embodiment mode are shown in  FIGS. 7A  to  7 D.  
         [0077]     For electronic devices manufactured using a light-emitting device of the present embodiment mode, a camera such as a video camera, a digital camera, or the like; a goggle-type display; a navigation system; an audio reproducing system (for example, a car audio system, an audio component system, or the like); a computer; a game machine; a handheld terminal (for example, a portable computer, a cellular telephone, a portable game machine, an electronic book reader, or the like); an image reproducing device (to be specific, a device that can play and includes a display device that can display images for recording media such as a Digital Versatile Disc (DVD) and the like); and the like can be given. Some specific examples thereof are shown in  FIGS. 7A  to  7 D.  
         [0078]     The television of  FIG. 7A  is a television device manufactured with a light-emitting device of the present embodiment mode and includes a case  9101 , a support stand  9102 , a display  9103 , speakers  9104 , video input terminals  9105 , and the like. The display  9103  of this television device is one in which the same light-emitting elements as those described in the present embodiment mode are arranged in the form of a matrix. The light-emitting elements have the characteristics of high luminous efficiency and low drive voltage. In addition, short-circuiting due to impacts or the like caused by an external source can be prevented. Because the display  9103  made up of the light-emitting elements has the same characteristics, deterioration in the picture of this television device is reduced and low power consumption can be achieved. Through such characteristics, because deterioration compensating functions and power supply circuits can be greatly reduced in number or size, a reduction in the size and weight of the case  9101  and the support stand  9102  can be achieved. Because low power consumption, high picture quality, and a reduction in the size and weight of the television device produced using the light-emitting device of the present embodiment mode can be achieved, a device adapted for use in a household environment can be provided thereby.  
         [0079]     The computer of  FIG. 7B  is a computer manufactured with a light-emitting device of the present embodiment mode and includes a main body  9201 , a case  9202 , a display  9203 , a keyboard  9204 , an external connection port  9205 , a touchpad  9206 , and the like. The display  9203  of this computer is one in which the same light-emitting elements as those described in the present embodiment mode are arranged in the form of a matrix. The light-emitting elements have the characteristics of high luminous efficiency and low drive voltage. In addition, short-circuiting due to impacts or the like caused by an external source can be prevented. Because the display  9203  made up of the light-emitting elements has the same characteristics, deterioration in the image quality of this computer is reduced and a shift to low power consumption can be achieved. Through such characteristics, because deterioration compensating functions and power supply circuits can be greatly reduced in number or size, a reduction in the size and weight of the main body  9201  and the case  9202  can be achieved. Because low power consumption, high picture quality, and a reduction in the size and weight of the computer produced using the light-emitting device of the present embodiment mode can be achieved, a device adapted for use in an applicable environment can be provided thereby. In addition, a computer that has a display which is able to withstand impacts by an external source can be provided.  
         [0080]     The cellular phone of  FIG. 7C  is a cellular phone manufactured with a light-emitting device of the present embodiment mode and includes a main body  9401 , a case  9402 , a display  9403 , an audio input  9404 , an audio output  9405 , operation keys  9406 , an external connection port  9407 , an antenna  9408 , and the like. The display  9403  of this cellular phone is one in which the same light-emitting elements as those described in the present embodiment mode are arranged in the form of a matrix. The light-emitting elements have the characteristics of high luminous efficiency and low drive voltage. In addition, short-circuiting due to impacts or the like caused by an external source can be prevented. Because the display  9403  made up of the light-emitting elements has the same characteristics, deterioration in the image quality of this cellular phone is reduced and low power consumption can be achieved. Through such characteristics, because deterioration compensating functions and power supply circuits can be greatly reduced in number or size, a reduction in the size and weight of the main body  9401  and the case  9402  can be achieved. Because low power consumption, high picture quality, and a reduction in the size and weight of the cellular phone produced using the light-emitting device of the present embodiment mode can be achieved, a device adapted for portable use can be provided thereby. In addition, a cellular phone that has a display which is able to withstand impacts by an external source can be provided.  
         [0081]     The camera of  FIG. 7D  is a camera manufactured with a light-emitting device of the present embodiment mode and includes a main body  9501 , a display  9502 , a case  9503 , an external connection port  9504 , a remote control receiver  9505 , an image receiver  9506 , a battery  9507 , an audio input  9508 , operation keys  9509 , an eyepiece  9510 , and the like. The display  9502  of this camera is one in which the same light-emitting elements as those described in the present embodiment mode are arranged in the form of a matrix. The light-emitting elements have the characteristics of high luminous efficiency and low drive voltage, and short-circuiting due to impacts or the like caused by an external source can be prevented. Because the display  9502  made up of the light-emitting elements has the same characteristics, deterioration in the image quality of this camera is reduced and low power consumption can be achieved. Through such characteristics, because deterioration compensating functions and power supply circuits can be greatly reduced in number or size, a reduction in the size and weight of the main body  9501  can be achieved. Because low power consumption, high picture quality, and a reduction in the size and weight of the camera produced using the light-emitting device of the present embodiment mode can be achieved, a device adapted for portable use can be provided thereby. In addition, a camera that has a display which is able to withstand impacts by an external source can be provided.  
         [0082]     As described above, the scope and field of application of the light-emitting device of the present invention are extremely wide, and it is possible to apply the light-emitting device to electronic devices of any field. Use of the light-emitting device of the present invention allows an electronic device with a highly reliable display with low power consumption to be provided.  
         [0083]     This application is based on Japanese Patent Application serial No. 2006-058737 filed with the Japan Patent Office on Mar. 3, 2006, the contents of which are hereby incorporated by reference.