Utilizing nanowire for generating white light

One embodiment in accordance with the invention is an apparatus that can include a light emitting diode that is for of outputting light in the blue wavelength. Furthermore, the apparatus can also include a nanowire or nanoparticle coupled to a surface of the light emitting diode. Additionally, the apparatus can include an electrode coupled to the light emitting diode, wherein the nanowire or nanoparticle is for receiving and converting the light into red and green light that is output from the nanowire or nanoparticle.

BACKGROUND

Currently, there are at least four different ways to fabricate a white light source with light emitting diode (LED) technology. For example, the first technique involves utilizing a red LED, a blue LED, and a green LED. The combined output of these LEDs is mixed or combined to create white light. However, this technique can be expensive, in particular when creating a large area white light source, since it involves many groups of at least three LEDs to create the white light.

The second technique involves adhering yellow phosphor granules to a blue LED with an epoxy. As such, part of the blue light output by the LED excites the yellow phosphor causing it to emit a broad range of spectrum covering red and green light that combines with the blue light of the LED to make white light. However, some of the problems associated with this technique are that it has low conversion efficiency at the phosphor granules and the epoxy tends to degrade as it is exposed to the blue light from the blue LED, causing it to become cloudy.

The third technique involves adhering red, green and blue (RGB) phosphor granules to a ultra-violet (UV) LED with an epoxy. As such, the UV light output by the LED excites the RGB phosphor causing them to emit a broad range of spectrum covering red, green and blue light, resulting in the generation of white light. However, some of the problems associated with this technique are that it has, as in the second technique described above, low conversion efficiency at the phosphor granules and the epoxy tends to degrade as it is exposed to the UV light from the UV LED causing it to become cloudy.

The fourth technique involves an effort to try and grow a gallium nitride (GaN) LED structure on a zinc oxide (ZnO) substrate. As such, the blue light output by the GaN LED excites the ZnO substrate, which generates red and green light. When these red and green lights are combined with the original blue light from the GaN LED, it results in white light. However, one of the problems associated with this technique is that it is very difficult to grow a GaN LED on a ZnO substrate without including defects within the GaN LED since the two different materials have very different physical characteristics. It is noted that the defects within the GaN LED can cause it to adversely degrade. Another problem associated with this technique is the fact that the ZnO substrate is currently very expensive to purchase, thereby adversely driving up the cost of the overall product.

Therefore, it is desirable to address one or more of the above issues.

DETAILED DESCRIPTION

Reference will now be made in detail to various embodiments in accordance with the invention, examples of which are illustrated in the accompanying drawings. While the invention will be described in conjunction with various embodiments, it will be understood that these various embodiments are not intended to limit the invention. On the contrary, the invention is intended to cover alternatives, modifications and equivalents, which may be included within the scope of the invention as construed according to the Claims. Furthermore, in the following detailed description of various embodiments in accordance with the invention, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be evident to one of ordinary skill in the art that the invention may be practiced without these specific details. In other instances, well known methods, procedures, components, and circuits have not been described in detail as not to unnecessarily obscure aspects of the invention.

FIG. 1is a side perspective view of an exemplary white light source apparatus100that includes one or more nanowires110grown (or formed) in a substantial vertical (or “column”) configuration in accordance with various embodiments of the invention. Specifically, within apparatus100, one or more single crystalline nanowires110can be grown on one or more surfaces of a blue or ultraviolet (UV) light emitting diode (LED)102. As such, when the blue LED102generates light within the blue wavelength (represented by an open-ended arrowhead), some of that blue light108can be absorbed and converted by the nanowires110into light within a wide range of spectrum covering green and red light104(represented by a solid closed-ended arrowhead). Therefore, the apparatus100enables the blue light108of the blue LED102to be mixed efficiently with the green and red light104generated by the nanowires110to produce an overall effect of white light. Note that apparatus100can be referred to as a white LED100. In addition, when a UV LED102generates light within the UV wavelength (represented by an open-ended arrowhead), some of that UV light108can be absorbed and converted by the nanowires110into light within a wide range of spectrum covering blue, green and red light104(represented by a solid closed-ended arrowhead). Therefore, the apparatus100enables the red, green and blue light104to be mixed efficiently and produces an overall effect of white light. In this manner, apparatus100can be referred to as a white LED100.

Within apparatus100, it is understood that the blue or UV LED102can be implemented with gallium nitride (GaN) and related alloys such as aluminum gallium nitride (AlGaN), but is not limited to such. It is understood that any type of LED that is able to excite the nanowires110can be utilized within apparatus100. The nanowires110of apparatus100can be implemented with, but is not limited to, a group II-VI compound semiconductor material (e.g., zinc oxide (ZnO), zinc selenide (ZnSe), cadmium selenide (CdSe), etc.) and related alloys, a group III-V compound semiconductor material (e.g., gallium arsenide (GaAs), indium phosphide (InP), etc.) and related alloys, any material having an ability to emit a broad range of spectrum covering red, green and blue, i.e. white light when mixed, as a result of absorbing light at around 500 nanometers (nm)+/−150 nm that comes from LED102, and any material having a band gap approximately 500 nanometers (nm)+/−150 nm. Moreover, it is pointed out that nanowires110can be heavily doped as part of apparatus100. Note that when the nanowires110are doped heavily, the absorption spectrum gets broader thereby enabling the nanowires110to emit or output a broader spectrum when excited by the reception of the light108from the LED102. For example, “heavily” doped ZnO (Eg=3.3 eV) can emit a desirable broad spectrum for generating white light when excited by the blue light108output by a blue LED102(based on it being implemented with GaN and related alloys such as indium gallium arsenide (InGaAs)). Note that if the nanowires110are implemented with ZnO, they can be doped with magnesium (Mg), beryllium (Be), calcium (Ca), strontium (Sr), barium (Ba), radium (Ra), or any other material above or below magnesium within the periodic table. The heavily doping of the ZnO nanowires can be greater than 5×1019cm−3, but is not limited to such. It is understood that if the nanowires110are implemented with group III-V compound semiconductor material and related alloys, they can be heavily doped with, but are not limited to, zinc (Zn), silicon (Si), carbon (C), or anything within group II or group VI can be used as the dopant.

WithinFIG. 1, it is noted that the nanowires110can be epitaxially grown on the LED102substrate. In various embodiments, the epitaxial growth process can include, but is not limited to, utilizing vapor phase synthesis. When the nanowires110are grown on the LED102, constraints associated with the lattice mismatch are much more relaxed and there are just minimum lattice mismatch problems. It is understood that the fabricating of apparatus100can include utilizing a high quality LED structure for LED102, while the nanowires110that are grown (or formed) do not have to be high quality as long as the nanowires110have an ability to convert the light emitted by the LED102into a broad range of spectrum covering red, green and blue light for a UV LED102or red and green light for a blue LED102. Furthermore, the nanowires110can be either aligned along a specific direction with respect to the LED102or randomly oriented. Therefore, the expense of manufacturing apparatus100is advantageously reduced because of the above mentioned factors.

Within apparatus100, it is appreciated that when a blue LED102is implemented with a high quality GaN and related alloys, it can produce light having a wavelength of approximately 470 nm. Subsequently, the nanowires110(which can be heavily doped) can be formed or grown on the blue LED102. As such, the blue light108output by the blue LED102can go into the nanowires110and get converted into a spectrum that covers approximately 520-630 nm, which is basically red and green light. It is understood that when the blue LED light108enters the nanowires110, the energy of the blue light108can be converted from a high energy to a lower energy.

WithinFIG. 1, it is appreciated that the nanowires110can be grown with different doping levels thereby resulting in covering various emission spectrum ranges among nanowires110. For example, one or more of nanowires110can be grown with a first type of doping having a first range of emission spectrum while one or more of nanowires110can be grown with a second type of doping having a different range of emission spectrum, and so forth. In this manner, the color rendering, one of the important characteristics of white light, of the resulting white light can be tuned. It is understood that the nanowires110can be grown having one doping level resulting in an emission spectrum or the nanowires110can be grown having various levels of dopings.

The apparatus100can include, but is not limited to, electrodes106that can be electrically coupled to the blue or UV LED102. The electrodes106can enable a current or voltage source and voltage ground (neither shown) to be coupled to the blue or UV LED102. Furthermore, one or more nanowires110can be grown, formed, or disposed on the blue or UV LED102. Note that the one or more surfaces of the LED102that the one or more nanowires110can be grown, formed, or disposed on can include non-single crystal material such as, but not limited to, polycrystalline silicon, amorphous silicon, poly-crystal (grain size is in the range of micro meter to nano meter) diamond and related carbon-based materials and/or microcrystalline silicon, and the like.

FIG. 2is a side perspective view of an exemplary white light source apparatus200that can include one or more nanowires110dispersed (or sprinkled or grown or formed) in a random configuration in accordance with various embodiments of the invention. It is noted that apparatus200is similar to apparatus100ofFIG. 1. However, the nanowires110of apparatus200can be in a configuration where the nanowires110can be aligned along a specific orientation with respect to the LED102, randomly aligned or simply laid down on one or more surfaces of the LED102. Even though configured in these ways, the apparatus200can be implemented and operate in any manner similar to apparatus100, as described herein.

Specifically, if the nanowires110are dispersed or sprinkled onto one or more surfaces of the LED102in a random configuration, the nanowires110could have been grown on some foreign substrate (not shown), scraped off that foreign substrate, and then dispersed or sprinkled onto the LED102. Furthermore, the nanowires110can be coupled or attached to the fabricated blue102in a wide variety of ways. For example in various embodiments, the nanowires110can be coupled or attached by utilizing a polymer rinse. In various embodiments, the nanowires110can be coupled or attached by utilizing an atomic layer deposition (ALD) process (as shown inFIG. 5) or any other analogous film deposition processes. In this manner, a coating can be formed over the nanowires110of a transparent dielectric (e.g., aluminum oxide (AlOx)) that is transparent to visible light. In various embodiments, if the nanowires110are not dispersed or sprinkled onto the LED102, the nanowires110can be grown on one or more surfaces of the LED102.

WithinFIG. 2, the apparatus200can include, but is not limited to, electrodes106that can be electrically coupled to the blue or UV LED102. The electrodes106can enable a voltage source and voltage ground (neither shown) to be coupled to the blue or UV LED102. Additionally, one or more nanowires110can be dispersed, sprinkled, grown, formed, or disposed on the blue or UV LED102. Note that when a blue LED102generates light within the blue wavelength108(represented by an open-ended arrowhead), some of that blue light108can be absorbed and converted by the nanowires110into light within a wide range of spectrum covering green and red light104(represented by a solid closed-ended arrowhead). Additionally, when the UV LED102generates light within the UV wavelength108(represented by an open-ended arrowhead), some of that UV light108can be absorbed and converted by the nanowires110into light within a wide range of spectrum covering blue, green and red light104(represented by a solid closed-ended arrowhead).

FIG. 3is a side perspective view of an exemplary white light source apparatus300that includes one or more nanowires110grown (or formed) in a random configuration in accordance with various embodiments of the invention. It is noted that apparatus300is similar to apparatus100ofFIG. 1. However, the nanowires110of apparatus300can be in a configuration wherein the nanowires110can be aligned or randomly aligned. Specifically, the nanowires110of apparatus300can be grown (or formed) on the blue or UV LED102in any configuration. Even though configured in these ways, the apparatus300can be implemented and operate in any manner similar to apparatus100, as described herein.

WithinFIG. 3, the apparatus300can include, but is not limited to, electrodes106that can be electrically coupled to the blue or UV LED102. The electrodes106can enable a current or voltage source and voltage ground (neither shown) to be coupled to the blue or UV LED102. Additionally, one or more nanowires110can be dispersed, sprinkled, grown, formed, or disposed on the blue or UV LED102as shown in apparatus300. It is appreciated that when the blue LED102generates light within the blue wavelength108(represented by an open-ended arrowhead), some of that blue light108can be absorbed and converted by the nanowires110into light within a wide range of spectrum covering green and red light104(represented by a solid closed-ended arrowhead). Furthermore, when the UV LED102generates light within the UV wavelength108(represented by an open-ended arrowhead), some of that UV light108can be absorbed and converted by the nanowires110into light within a wide range of spectrum covering blue, green and red light104(represented by a solid closed-ended arrowhead).

FIG. 4is a side perspective view of an exemplary white light source apparatus400that includes one or more nano-particles110′ dispersed (or sprinkled or grown or formed) in a random configuration in accordance with various embodiments of the invention. It is noted that apparatus400is similar to apparatus100ofFIG. 1. However, the nano-particles110′ of apparatus400can be in a configuration where they can be arranged in an array or in a random manner. Even though configured in these ways, the apparatus400can be implemented and operate in any manner similar to apparatus100, as described herein.

Specifically, the single crystalline nano-particles110′ can be implemented in any manner similar to nanowires110, as described herein. It is noted that nano-particles110′ can be grown or formed in any manner similar to nanowires110. The growth technique for nano-particles110′ can just involve growing something (or anything) utilizing any nanowire growth technique. Note that the one or more surfaces of the LED102that the one or more nano-particles110′ can be grown, formed, or disposed on can include non-single crystal material such as, but not limited to, polycrystalline silicon, amorphous silicon, poly-crystal (grain size is in the range of micro meter to nano meter) diamond and related carbon-based materials and/or microcrystalline silicon, and the like. It is pointed out that there is a very convenient cheap chemical method to produce nano-particles110′. However the nano-particles110′ are formed, they can be sprinkled or dispersed onto one or more surfaces of the LED102.

WithinFIG. 4, if the nano-particles110′ are dispersed or sprinkled onto one or more surfaces of the blue LED102in any configuration, the nano-particles110′ can be coupled or attached to the fabricated LED102in a wide variety of ways. For example in various embodiments, the nano-particles110′ can be coupled or attached by utilizing a polymer rinse. In various embodiments, the nano-particles110′ can be coupled or attached to the LED102by utilizing, for example, an atomic layer deposition (ALD) process as shown inFIG. 5or any other analogous film deposition processes.

Specifically,FIG. 5is a side section view of an exemplary technique500for coupling one or more nano-particles110′ (or nanowires110) to a LED (e.g.,102) in accordance with various embodiments of the invention. For example, a coating502can be formed over the nano-particles110′ (or nanowires110) and the one or more surfaces of the LED102of a transparent dielectric (e.g., aluminum oxide (AlOx)) that is transparent to visible light. In this manner, the coating502couples or attaches the one or more nano-particles110′ (or nanowires110) to the LED102. In various embodiments, if the nano-particles110′ (or nanowires110) are not dispersed or sprinkled onto the LED102, the nano-particles110′ (or nanowires110) can be grown on one or more surfaces of the LED102.

WithinFIG. 4, the apparatus400can include, but is not limited to, electrodes106that can be electrically coupled to the blue or UV LED102. The electrodes106can enable a current or voltage source and voltage ground (neither shown) to be coupled to the blue or UV LED102. Moreover, one or more nano-particles110′ can be dispersed, sprinkled, grown, formed, or disposed on the blue or UV LED102. It is understood that when the blue LED102generates light within the blue wavelength108(represented by an open-ended arrowhead), some of that blue light108can be absorbed and converted by the nano-particles110′ into light within a wide range of spectrum covering green and red light104(represented by a solid closed-ended arrowhead). It is further understood that when the UV LED102generates UV light within the UV wavelength108(represented by an open-ended arrowhead), some of that UV light108can be absorbed and converted by the nano-particles110′ into light within a wide range of spectrum covering red, green and blue light104(represented by a solid closed-ended arrowhead).

FIG. 6is a side perspective view of an exemplary white light source apparatus600that includes one or more nano-particles (e.g.,110′,110″, and110′″) dispersed or sprinkled or grown or formed in an array or in a random manner in accordance with various embodiments of the invention. It is noted that apparatus600is similar to apparatuses100and400ofFIGS. 1 and 4, respectively. However, the nano-particles110′,110″ and110′″ of apparatus600can be doped differently or made of different materials from each other. Even though configured in this manner, the apparatus600can be implemented and operate in any manner similar to apparatuses100and400, as described herein. The one or more nano-particles110′,110″ and110′″ can each be implemented in any manner similar to the one or more nanowires110, described herein.

Within apparatus600there are three groups of nano-particles that have each been doped differently or made of different materials. Specifically, there can be a group of first doped nano-particles (or nano-particles made of first material)110′ having a first range of emission spectrum104, a group of second doped nano-particles (or nano-particles made of second material)110″ having a different second range of emission spectrum104′, and a group of third doped nano-particles (or nano-particles made of third material)110′″ having a different third range of emission spectrum104″. In this manner, for example, the spectrum width of wavelength around red, green and blue lights104,104′ and104″ can be tuned to produce various white lights having different color rendering.

WithinFIG. 6, the apparatus600can include, but is not limited to, electrodes106that can be electrically coupled to the blue or UV LED102. The electrodes106can enable a current or voltage source and voltage ground (neither shown) to be coupled to the blue or UV LED102. Additionally, one or more nano-particles110′,110″ and110′″ can be dispersed, sprinkled, grown, formed, or disposed on the blue or UV LED102. It is noted that when the blue LED102generates light within the blue wavelength (represented by an open-ended arrowhead), some of that blue light108can be absorbed and converted by the nano-particles110′,110″ and110′″ into light within the wavelength of green and red light104,104′ and104″, respectively (represented by a solid closed-ended arrowhead). When the UV LED102generates light within the ultraviolet wavelength (represented by an open-ended arrowhead), some of that ultraviolet light108can be absorbed and converted by the nano-particles110′,110″ and110′″ into light within the wavelength of red, green and blue light104,104′ and104″, respectively (represented by a solid closed-ended arrowhead).

FIGS. 7A and 7Bare side perspective views of fabricating exemplary apparatuses700and720that each include one or more nanowires110in accordance with various embodiments of the invention. Specifically, withinFIG. 7A, one or more nanowires110can be grown or formed on a foreign substrate (e.g., glass, transparent material, and the like)702thereby resulting in apparatus700. Note that the foreign substrate702can be foreign to the LED102. Next, withinFIG. 7B, the foreign substrate702and its nanowires110of apparatus700can be inverted (or flipped over) and then the nanowires110can be abutted or coupled to a blue or UV LED102, thereby forming apparatus720. In this manner, the nanowires110and the LED102of apparatus720can be implemented and operate in any manner similar to apparatuses100,200, and300as described herein.

The apparatus720ofFIG. 7Bcan include, but is not limited to, electrodes106that can be electrically coupled to the blue or UV LED102. The electrodes106can enable a current or voltage source and voltage ground (neither shown) to be coupled to the blue or UV LED102. Additionally, one or more nanowires110can be dispersed, sprinkled, grown, formed, or disposed on the foreign substrate702. Moreover, it is understood that one or more of the nanowires110can be doped differently from each other, as described herein. It is understood that the one or more nanowires110ofFIGS. 7A and 7Bcan be configured in any manner shown and/or described herein, but is not limited to such.

FIGS. 8A and 8Bare side perspective views of fabricating exemplary apparatuses800and820that each include one or more nano-particles110′ in accordance with various embodiments of the invention. Specifically, withinFIG. 8A, one or more nanoparticles110′ can be grown or formed on a foreign substrate (e.g., glass, transparent material, and the like)702thereby resulting in apparatus800. Note that the foreign substrate702can be foreign to the LED102. Next, withinFIG. 8B, the foreign substrate702and its nanoparticles110′ of apparatus800can be inverted (or flipped over) and then the nanoparticles110′ can be abutted or coupled to a blue or UV LED102, thereby forming apparatus820. In this manner, the nanoparticles110′ and the LED102of apparatus820can be implemented and operate in any manner similar to apparatuses100,200, and300as described herein.

The apparatus820ofFIG. 8Bcan include, but is not limited to, electrodes106that can be electrically coupled to the blue or UV LED102. The electrodes106can enable a current or voltage source and voltage ground (neither shown) to be coupled to the blue or UV LED102. Additionally, one or more nanoparticles110′ can be dispersed, sprinkled, grown, formed, or disposed on the foreign substrate702. Furthermore, it is understood that one or more of the nanoparticles110′ can be doped differently from each other, as described herein. It is understood that the one or more nanoparticles110′ ofFIGS. 8A and 8Bcan be configured in any manner shown and/or described herein, but is not limited to such.

FIG. 9is a flow diagram of a method900for fabricating a white light source apparatus that includes one or more nanowires or nano-particles in accordance with various embodiments of the invention. Method900includes exemplary processes of various embodiments of the invention that can be carried out by a processor(s) and electrical components under the control of computing device readable and executable instructions (or code), e.g., software. The computing device readable and executable instructions (or code) may reside, for example, in data storage features such as volatile memory, non-volatile memory and/or mass data storage that can be usable by a computing device. However, the computing device readable and executable instructions (or code) may reside in any type of computing device readable medium. Although specific operations are disclosed in method900, such operations are exemplary. Method900may not include all of the operations illustrated byFIG. 9. Also, method900may include various other operations and/or variations of the operations shown byFIG. 9. Likewise, the sequence of the operations of method900can be modified. It is noted that the operations of method900can be performed by software, by firmware, by electronic hardware, or by any combination thereof.

Specifically, a light emitting diode can be fabricated for outputting light in the blue wavelength and/or the ultraviolet wavelength. One or more nanowires or nano-particles can be disposed on one or more surfaces of the light emitting diode. It is noted that the one or more nanowires or nano-particles can each be for receiving and converting the light into either red and green light, or red, green and blue light that is output from each nanowire or nano-particle.

At operation902ofFIG. 9, a light emitting diode (e.g.,102) can be fabricated for outputting light (e.g.,108) in the blue wavelength and/or the ultraviolet wavelength. Note that operation902can be implemented in a wide variety of ways. For example, operation902can be implemented in any manner similar to that described herein, but is not limited to such.

At operation904, one or more nanowires or nanoparticles (e.g.,110,110′,110″ and/or110′″) can be disposed on one or more surfaces of the light emitting diode. It is noted that the one or more nanowires or nano-particles can each be for receiving and converting the light (e.g.,108) into either red and green light (e.g.,104,104′ and/or104″) or red, green and blue light (e.g.,104,104′ and/or104″) that can be output from each nanowire or nanoparticle. It is understood that operation904can be implemented in a wide variety of ways. For example in various embodiments, the disposing of the one or more nanowires (or nanoparticles) can include growing them from one or more surfaces of the light emitting diode. In various embodiments, the disposing of the one or more nanowires (or nanoparticles) can include utilizing an atomic layer deposition technique or any other analogous film deposition techniques. In various embodiments, the disposing of the one or more nanowires (or nanoparticles) can include a first nanowire (or a first nanoparticle) of the plurality of nanowires (or nanoparticles) being doped differently than a second nanowire (or nanoparticle) of the plurality of nanowires (or nanoparticles). In various embodiments, the disposing of the one or more nanowires (or nanoparticles) can include utilizing a substrate that is foreign (e.g.,702) to the light emitting diode. The one or more nanowires (or nanoparticles) can be implemented with, but are not limited to, a group II-VI compound semiconductor materials and related alloys, a group III-V compound semiconductor materials and related alloys, any material having an ability to emit a broad range of spectrum covering red, green and blue, i.e. white light when mixed, as a result of absorbing light at around 500 nanometers (nm)+/−150 nm that comes from LED102, and any material having a band gap approximately 500 nanometers (nm)+/−150 nm. The light emitting diode can include gallium nitride (GaN), aluminum gallium nitride (AlGaN), but is not limited to such. It is noted that operation904can be implemented in any manner similar to that described herein, but is not limited to such.

In accordance with various embodiments of the invention, it is understood that each of apparatuses100,200,300,400,600,700,720,800and820can be implemented to include the combination of one or more nanowires (e.g.,110) along with one or more nanoparticles (e.g.,110′). In accordance with various embodiments of the invention, it is understood that technique500and method900can each be implemented to include the combination of one or more nanowires (e.g.,110) along with one or more nanoparticles (e.g.,110′).

The foregoing descriptions of various specific embodiments in accordance with the invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The invention can be construed according to the Claims and their equivalents