Patent Publication Number: US-7224001-B2

Title: Semiconductor light source

Description:
BACKGROUND OF INVENTION 
   The invention relates to the field of light sources and illumination devices. More particularly, the invention relates to semiconductor light sources and illumination devices useful for providing visible light in order to partially or fully illuminate a space occupied by or viewed by humans, such as residential space, commercial space, outdoor space, the interior or exterior of a vehicle, etc. 
   In the prior art, light emitting diodes (“LED&#39;s”) and other semiconductor light sources were traditionally used for panel displays (such as laptop computer screens), signal lighting, and other instrumentation purposes. LED&#39;s are desirable because they are a high efficiency light source that uses substantially less energy and creates less heat than typical prior art light sources such as incandescent and halogen lights. Prior art semiconductor light sources have not been successfully and economically used to illuminate physical spaces. Additionally, in the prior art, LED&#39;s were typically individually packaged in a module, either with or without a focus dome on the module. Typical prior art LED modules lack high light intensity due to the size of the LED chips used. Further, arranging a sufficient number of prior art LED modules to generate high light intensity, such as use of a stack, lamp or array, took an excessive amount of physical space and created unmanageable amounts of heat. Consequently, in the prior art, LED&#39;s and other semiconductor light sources were not suitable for replacing the traditional tungsten light bulbs. 
   U.S. Pat. No. 5,941,626 discloses a long light emitting apparatus that uses a plurality of LED lamps (modules) connected in series. The LED modules are spaced apart and appear to be intended for decorative use, such as on street lamp poles and on Christmas trees. 
   U.S. Pat. No. 5,160,200 discloses a wedge-base LED bulb housing. The patent depicts a plurality of separate LED modules electrically connected to a wedge base. 
   U.S. Pat. No. 4,675,575 discloses light-emitting diode assemblies such as a mono-color or bi-color light string system. Each LED is in an envelope with light conducting optical spheres for light transmission and dispersion. The LED string system appears adapted for decorative use, such as for lighting Christmas trees. 
   A distinct need is felt in the prior art for a semiconductor light source for use in illuminating a space with single color light in the visible range and which can efficiently dissipate the heat that they produce. Presently, that application is served by incandescent and fluorescent lights which have high energy consumption, high heat generation, and short useful life compared to the invented semiconductor light sources. 
   SUMMARY OF INVENTION 
   It is an object of some embodiments of the invention to provide a semiconductor light source capable of illuminating a space with visible light. These and other objects of various embodiments of the invention will become apparent to persons of ordinary skill in the art upon reading the specification, viewing the appended drawings, and reading the claims. 

   
     BRIEF DESCRIPTION OF DRAWINGS 
       FIG. 1  depicts a semiconductor light source of one embodiment of the invention using a high power chip or array arrangement. 
       FIG. 2  depicts a semiconductor light source of one embodiment of the invention using high power surface mount LED chip modules or lamps. 
       FIG. 3   a  depicts an LED with an insulating substrate. 
       FIG. 3   b  depicts a detailed view of an LED structure on a sapphire substrate. 
       FIG. 3   c  depicts an LED with a conducting substrate. 
       FIG. 3   d  depicts a detailed view of an LED structure on a sapphire substrate. 
       FIG. 3   e  depicts a VCSEL chip on an insulating substrate. 
       FIG. 3   f  depicts a detailed view of a VCSEL chip on a insulative substrate. 
       FIG. 3   g  depicts a VCSEL chip on a conductive substrate. 
       FIG. 3   h  depicts a detailed view of a VCSEL chip in a conductive substrate. 
       FIG. 4   a  depicts a top view of an LED array on a single chip with an insulating substrate. 
       FIG. 4   b  depicts a top view of an LED array on a single chip with a conductive substrate. 
       FIG. 4   c  depicts a top view of a VCSEL array on a single chip with an insulating substrate. 
       FIG. 4   d  depicts a top view of a VCSEL array on a single chip with a conductive substrate. 
       FIG. 5   a  depicts a semiconductor chip of the invention that emits single color light using a conversion layer. 
       FIG. 5   b  depicts a semiconductor chip of the invention that emits single color light using a phosphor coating. 
       FIG. 6  depicts a cross sectional view of a heat sink of the invention using a fan and TE cooler to circulate air and remove heat. 
       FIG. 7   a  depicts a single chip or single array chip package. 
       FIG. 7   b  depicts a multiple chip package. 
       FIG. 8   a  depicts a chip package with phosphor covering on the semiconductor. 
       FIG. 8   b  depicts a chip package with a uniform phosphor coating. 
       FIG. 9  depicts a high power LED package. 
       FIG. 10  depicts an LED or laser light source located in a light enclosure having a phosphor coating. 
       FIG. 11  depicts a power supply module with fitting for a light source of the invention. 
   

   DETAILED DESCRIPTION  
   Referring to  FIG. 1 , one embodiment of the invention is depicted. In this embodiment of the invention, a semiconductor light source  100  is depicted. The light source  100  includes a traditional bulb-shaped enclosure  101 . The enclosure  101  may be of any desired shape, including spherical, cylindrical, elliptical, domed, square, n-sided where n is an integer, or otherwise. The enclosure may be made from any desired light transparent or translucent materials, including glass, plastic, polycarbonate, and other light transparent materials. 
   The enclosure  101  has an exterior surface  101   a  and an interior surface  101   b.  The exterior surface  101   a  may be smooth and glossy, matte, or another finish or texture. The exterior surface  110   a  may be coated or painted with desired materials. The interior surface  101   b  may optionally include an appropriate coating, such as a luminous powder coating. Examples of luminous powder coating that may be used in the invention include YAG:Ce or other phosphor powders or coatings. For example, if the light source uses blue LED&#39;s to generate light, but it is desired to illuminate a room with white light, the interior surface  101   b  maybe covered with a phosphor coating to convert blue light into white light. Any wavelength-modifying coating such as phosphor or another coating may be used. In some preferred embodiments of the invention, it is intended to convert light emitted by a semiconductor chip in the wavelength range of about 200 to about 700 nm. to white light. 
   The enclosure  101  encloses an interior volume  102  which may be a vacuum, or may contain a gas such as ordinary air, an inert gas such as argon or nitrogen, or any other desired gas. In some embodiments of the invention, a gas will be included within the interior volume  102  for the purpose of avoiding oxidation of the heat sink and the semiconductor. 
   The enclosure  101  may be mounted to a support  105 . The support  105  may be a separate component or may be integral with the base  103 . The base  103  may be configured as a fitting or connector for use in a desired light socket, such as a traditional light socket. In such case, the base  103  would also include electrodes  103   a  and  103   b  for making electrical connection with a power source. 
   Located within the interior volume  102  is at least one heat sink  104 . The heat sink  104  may be of any desired shape, depending on the application. As depicted, the heat sink  104  has a generally flat or planar top  104   a,  and a plurality of generally flat or planar panels or compartment  104   b,    104   c,    104   d,    104   e,    104   f,    104   g,    104   h,    104   i,  etc. each of which may host a single or an array of semiconductor devices capable of producing light. The heat sink  104  may be shaped otherwise, with curved or rounded sides. 
   If the heat sink  104  may be mounted on a support  105 , the support  105  may be designed in order to place the heat sink in the most desirable position within the interior volume  102  so that semiconductors located on the heat sink may emit light that will be transmitted in a diffuse or focused pattern through the enclosure  101 . 
   Mounted on the heat sink  104  are at least one semiconductor device  106 . The semiconductor device(s)  106  may be arranged in this embodiment of the invention to transmit light in all directions except through the base  103 , or in a manner to direct light in a specific direction. The semiconductor devices may be any semiconductor devices capable of emitting light, such as LED&#39;s, LED arrays, VCSEL&#39;s, VCSEL arrays, photon recycling devices that cause a monochromatic chip to emit white light, and others. 
   The semiconductor devices  106  are electrically connected to each other via electrical connections  107 . Lead wires  108   a  and  108   b  are used to provide the semiconductor devices  106  with electrical power. As desired, the heat sink may serve as a positive or negative electrical connection for the semiconductor devices. 
   The heat sink  104  may be any material capable of conducting heat away from the semiconductor devices. Examples of suitable materials include copper, aluminum, silicon carbide, boron nitride and others known to have a high coeffecient of thermal conductivity. 
   In order to provide suitable electrical power to the semiconductor devices, an AC/DC converter (not shown in this fixture) is utilized. This will permit the invented semiconductor light source to be powered by 110 V. or 220 V. AC power found in homes and businesses throughout the world. The AC/DC converter may be located in the base  103  or in another location. 
   In alternative embodiments of the invention, each semiconductor device may have its own individual heat sink, or two or more semiconductor devices may be located on the same heat sink. In some embodiments of the invention, the base may also serve as a heat sink, eliminating the need for a separate heat ink and thereby reducing cost. 
   Referring to  FIG. 2 , a semiconductor device  2220  in enclosure  2201  can be arranged to accommodate high power surface LED&#39;s. “High power”LED&#39;s means that the light output from each LED module is greater than 40 milliwatts. “Surface mount”LED&#39;s are LED&#39;s mounted directly on a heat sink, or other surface, in contrast with traditional LED lamps which have ordinary electrical leads for wiring and must be separately held in place. High power surface mount LED&#39;s are described in detail later in this document. 
   When high power LED&#39;s are used, all the components are the same as in  FIG. 1  except that a high power LED  2206  is used. It can be seen that the LED&#39;s  2206  are electrically connected with electrical connectors  2207  and are located on a heat sink  2204 . The heat sink  2204  has a plurality of heat sink faces  2210 ,  2211  and  2212  which are each generally planar and are arranged in angular orientation with each other in order to cause light from the LED&#39;s to be dispersed around a space to be illuminated. The heat sink faces can be oriented with respect to each other at any desired angle, but 45 degree angles are depicted in the figure so that face  2210  is perpendicular to face  2212 . A standard base  2203  is provided. 
   Any of the semiconductor light sources described below and others may be used in embodiments of the invention. 
     FIG. 3   a  depicts an LED chip with an insulating substrate  201 . The substrate  202  may be an appropriate material on which a semiconductor may be grown, such as sapphire, gallium arsenide, silicon carbide, gallium phosphorous, gallium nitride and others. The substrate  202  will also in this embodiment be electrically insulative. The semiconductor material  203  will emit light in all directions as indicated by arrows  204   a,    204   b,    204   c  and  204   d.  Positive  205   a  and negative  205   b  electrodes are provided for powering the chip. 
     FIG. 3   b  depicts an example of epitaxial layer configuration for the LED of  FIG. 3   a.  A light emitting diode on an electrically insulative substrate  1200  is depicted. The LED includes an electrically insulative substrate such as sapphire  1201 . The substrate serves as a carrier, pad or platform on which to grow the chip&#39;s epitaxial layers. The first layer placed on the substrate  1201  is a buffer layer  1202 , in this case a GaN buffer layer. Use of a buffer layer reduces defects in the chip which would otherwise arise due to differences in material properties between the epitaxial layers and the substrate. Then a conductive layer  1203  is provided, such as n-GaN. This layer acts as a connector for a negative electrode. Then a cladding layer  1204 , such as n-AlGaN, is provided. Cladding layers serve to confine the electrons as they jump from a conduction band to valance and give up energy that converts to light. An active layer  1205  p-InGaN is then provided where electrons jump from a conduction band to valance and emit energy which converts to light. On the active layer  1205 , another cladding layer  1206 , such as p-AlGaN is provided that also serves to confine electrons. A contact layer  1207  such as p+-GaN is provided that is doped for Ohmic contact. The contact layer  1207  has a positive electrode  1208  mounted on it, in this case an electrode that has a mount side on the contact layer  1207  that is Ni and an electrode face that is Au. A similar negative electrode is provide on a shelf of the first cladding layer  1203 . 
     FIG. 3   c  depicts an LED with a conducting substrate  210 . The substrate  211  must be an electrically conductive material on which a semiconductor ship may be grown, such as gallium arsenide, silicon carbide, gallium phosphorous, gallium nitride and others. A portion of the substrate  212  will serve as an electrode for powering the chip, in this case a negative electrode. The semiconductor material  213  will emit light in all directions as indicated by arrows  214   a,    214   b,    214   c  and  214   d.  A positive electrode  215  is provided, and the base  240  of the substrate  211  acts as a negative electrode. The base  240  is made of any conductive metal such as Au, Au/Ce, An/Zn and others. 
     FIG. 3   d  depicts epitaxial layer configuration for the LED of  FIG. 3   c.  A light emitting diode grown on an electrically conductive substrate  1210  is depicted. The LED includes an electrically conductive substrate such as SiC  1212 . The substrate serves as a carrier, pad or platform on which to grow the chip&#39;s epitaxial layers, and as a negative electrode in the chip. The first layer placed on the substrate  1212  is a buffer layer  1213 , in this case a GaN buffer layer. Next, a cladding layer  1214  is provided, such as n-GaN. An active layer  1215  p-InGaN is provided where energy is converted to light. On the active layer  1215 , another cladding layer  1216 , such as p-AlGaN is provided. A contact layer  1217  such as p+-GaN that has a positive electrode  1218  mounted on it. A negative electrode  1211  is provided at the base of the chip. 
     FIG. 3   e  depicts a VCSEL chip on an insulating substrate  220 . The substrate  221  has a volume of semiconductor material  222  on it. Positive electrodes  223   a  and  223   b  and negative electrodes  224  are provided for powering the chip, and light is emitted from the chip in directions generally indicated by arrows  225   a  and  225   b.    
     FIG. 3   f  depicts epitaxial layer configuration of the VCSEL chip of  FIG. 3   e  with an electrically insulative substrate  1220 . The chip  1220  includes a substrate  1221  that has electrically insulative properties such as sapphire. On top of the substrate  1221  there is a buffer layer  1222  such as GaN followed by a cladding layer and contact layer  1223  such as n-GaN. The cladding layer  1223  includes a negative electrode  1232   c.  Next, there is another cladding layer nGaInN  1224 . A reflective layer AlN/AlGaN MQW (multiple quantum wells)  1225  is provided. A cladding layer  1226  n-AlGaN is interposed between the reflective layer  1225  and the active layer  1227  GaInN MQW. The active layer  1227  is followed by another cladding layer p-AlGaN  1228  which is followed by a second reflective layer  1229  AlN/AlGaN MQW. Light emitted from the active layer reflects between the two reflective layers until it reaches an appropriate energy level and then lases, emitting a laser beam of light. The second reflective layer  1229  is followed by a cladding layer p AlGaN  1230  and a contact layer p+-GaN  1231 . The contact layer may be ring-shaped with a window opening  1233  and has one or more positive electrodes  1232   a  and  1232   b  which are contact areas. The negative electrode is created on the n-GaN layer. 
     FIG. 3   g  depicts a VCSEL chip on a conductive substrate  230 . The substrate  231  has a volume of semiconductor material  232  on it. Positive electrodes  233   a  and  233   b  are provided for powering the chip, and light is emitted from the chip in directions generally indicated by arrows  235   a  and  235   b.  The base  236  of the substrate  231  serves as a negative electrode. 
     FIG. 3   h  depicts epitaxial layer configuration of a VCSEL chip with an electrically conductive substrate  1239  such as that of  FIG. 3   g.  The chip  1239  includes a substrate  1241  that has electrically conductive properties such as SiC. The underside of the substrate  1241  has an electrode  1240 . On top of the substrate  1241  there is a buffer layer  1242  such as GaN followed by a cladding layer  1243  such as n-GaN. Next, there is another cladding layer NGaInN  1244 . A reflective layer using AlN/AlGaN MQW (multiple quantum wells)  1245  is then provided. A cladding layer  1246  n-AlGaN is interposed between the first reflective layer  1245  and the active layer  1247  GaInN MQW. The active layer  1247  is followed by another cladding layer p-AlGaN  1248  which is followed by a second reflective layer  1429  AlN/AlGaN MQW. The second reflective layer  1249  is followed by a cladding layer p AlGaN  1250  and a contact layer p+-GaN  1251 . The contact layer may have one or more positive electrodes  1252   a  and  1252   b  mounted on it. 
     FIG. 4   a  depicts a top view of an LED array on a single chip with a size a×b on an insulating substrate  301 . Each of sizes a and b is greater than 300 micro meters. Semiconductor materials  302  are located on an electrically insulative substrate (not shown). Positive  303  and negative  304  pads are provided, each in electrical connection with its respective metal strip  305  and  306  arranged in a row and column formation (8 columns shown) to create the array and power the chip. This enables the LED to emit high power light from a single chip. 
     FIG. 4   b  depicts a top view of an LED array on a single chip with a size a×b on a conductive substrate  310 . Each of sizes a and b is greater than 300 micro meters. Semiconductor materials  312  are located on an electrically conductive substrate (not shown). Positive pad  313  is provided in electrical connection with a metal strip  315  arranged in an array formation to power the chip. The substrate  310  serves as the negative electrode in the embodiment depicted. 
     FIG. 4   c  depicts a top view of a VCSEL array on a single chip with a size a×b on an insulating substrate  320 . Each of sizes a and b is greater than 300 micro meters. The chip  320  includes an electrically insulative substrate (not shown) on which a semiconductor material  332  is located covered by a panel  333 . The panel  333  may be an appropriate conductive material such as Au/Ce, Au/Zn and others. The panel  333  has a plurality of windows  334  in it to permit light produced by the semiconductor material  332  to be emitted for use. The panel  333  is electrically connected to conductive metal strip  340  and to an electrode pad  335 . A negative electrode pad  336  is also provided in electrical conduction with a metal strip  337  to power the chip. 
     FIG. 4   d  depicts a top view of a VCSEL array on a single chip with a dimension a×b on a conductive substrate  340 . Each of sizes a and b is greater than 300 micro meters. It includes a conductive substrate (not shown) on which a semiconductor material  341  is located. A conductive panel  342  overlays the semiconductor material  341 . A plurality of windows  343  are provided in the panel  342  to allow light produced by the chip to escape for us. A positive electrode pad  344  is provided which in conjunction with the electrically conductive substrate serving as a negative electrode power the chip. A negative electrode is provided on the bottom of the chip  340 . 
     FIGS. 5   a  and  5   b  depict a semiconductor chip system that emits white light. In  FIG. 5   a,  there is a GaN based semiconductor chip  2000  depicted. It includes a GaN system  5001  built on an insulative sapphire substrate  5002  capable of emitting blue light, the general structure of which is known in the prior art. A light conversion layer  5003  such as AlGaInP (aluminum gallium indium phosphate) adjacent the sapphire layer  5002  opposite the GaN system  5001 . Light emitted from the GaN system will travel through the sapphire layer  5002 , through the AlGaInP  5003  to exit the chip system. Some of the blue light will be absorbed by the AlGaInP to emit yellow light, and some of the blue light will be transmitted through the AlGaInP. The combination of blue and yellow light emitted by the chip according to arrows  5004   a,    5004   b  and  5004   c  will appear as white light to human eyes. Electrodes  5005  and  5006  are provided for electrical connection. Referring to  FIG. 5   b,  the chip  2000  is depicted following application of an exterior light conversion coating or layer  5007  such as phosphor. Light which exits through the phosphor such as  5004   a  will be converted in wavelength to white, making a useful light for illuminating physical spaces. A coating or layer to convert monochromatic light to white light may include phosphor powder, YAG/Ce and others. Such a coating or layer may be applied by the methods of brush coating, flow coating and evaporative coating. 
     FIG. 6  depicts a cross sectional view of a heat sink of the invention  401 . As depicted in this embodiment, a plurality of semiconductor chips or high power LED&#39;s  402  capable of emitting light are mounted in a well of the heat sink material  403  (surface mounting). The mounting of the chips or high power LED&#39;s may be achieved by use of a heat-conductive adhesive  404 , or by brazing or mechanical fixation. The heat sink material  403  is of sufficient thickness to conduct heat away from the chips  402  and keep the chips cool. Located within the heat sink  403 , a layer or lining of thermal electric material  405  may be installed. Thermal electric (“TE”) material experiences a reduction in temperature when voltage is applied to it. By applying a voltage to the TE material  405 , its temperature can be lowered and heat can be drawn from the heat sink material  403  that in turn is drawing heat away from the chips  402 . The TE material may line an air chamber  406 . The air chamber is open at its entrance  406   a  and at its exit  406   b.  A fan  407  may be placed in or near the air chamber  406  in order to cause air  408  to travel in the entrance  406   a,  through the air chamber  406  past the TE material  405  and out of the exit  406   b,  carrying heat with it. Such a system will increase efficiency of heat dissipation from the chips  402 . At the bottom of the heat sink, a fitting or connector may be provided that is threaded  409   a  and has an electrode  409   b  for installation into a traditional light socket. 
     FIG. 7   a  depicts a single chip or single array chip surface mount package  501 . It includes a semiconductor chip or array  502  capable of emitting light mounted in a well  503  of a heat sink  504 . The well  503  is provided with reflective sides to that light emitted from the sides of the chip or array  502  is reflected out of the well in order to provide useful illumination and to minimize heat buildup. The chip or array  502  may be mounted in the well  503  by use of a heat conductive adhesive  505  or by brazing or mechanical fixation. The heat conductive adhesive may also be used as a reflector to reflect light from the substrate in the direction of arrows  509   a  and  509   b.  Connection blocks  507  and  508  may be mounted on the heat sink  504  in order to facilitate electrical connection of the chip  502 . Light exits the chip as indicated by arrows  509   a,    509   b  and  509   c.    
     FIG. 7   b  depicts a multiple chip package  520 . It includes multiple wells  521   a,    521   b  and  521   c  on a heat sink  522  in which multiple chips or arrays  523   a,    523   b  and  523   c  are located. Connection blocks  524   a,    524   b,    524   c  and  524   d  are provided with lead wires  525   a,    525   b,    525   c,    525   d  and  525   f  in order to electrically power the chips or arrays. 
     FIG. 8   a  depicts a chip package with phosphor covering  601 . The package includes a heat sink  602  in which a well is located  603  for receiving a chip or array  604 . Connection blocks  605   a  and  605   b  and lead wires  606   a  and  606   b  may be used to electrically power the chip or array  604 . A thickness of phosphor  607  may be placed over the chip or array  604  in order to convert single wavelength light emitted from the chip or array into multiple wavelength white light useful for illumination of spaces used by humans.  FIG. 8   b  depicts another phosphor coated chip package  6000 . It includes a heat sink  6001  on which a light emitting chip  6002  is mounted in a receptacle  6005  on the heat sink. The chip  6002  does not fill the entirety of the receptacle  6005  so a transparent filler  6003  of a material transparent to the wavelength of light emitted by the chip  6002  is provided. Some transparent materials which may be used include epoxy, plastic and others. On the face of the chip  6002  opposite the heat sink  6001  a wavelength conversion coating or layer  6004  is provided to convert the light emitted by the chip to white light. A phosphor coating is preferred. 
     FIG. 9  depicts a high power surface mount LED package  901  useful in the invention. The LED package  901  includes a heat sink  902  formed from a material which can dissipate heat. A well  904  is formed in the heat sink in order to accept an LED, laser diode or semiconductor chip array  903  therein. The well  904  has walls  905  for reflecting light  906   a  and  906   b  emitted by the chip(s)  903 . An optional phosphor coating  907  is provided over the chip(s) to convert light emitted by the chip(s) to white light. The chip(s)  903  are secured to the heat sink  903  by use of adhesive  908 . The adhesive  908  may be heat conductive to aid in transmission of heat from the chips to the heat sink, and it may have light reflective properties to aid in reflection of light from the chips in the direction of arrows  906   a  and  906   b  in a usable direction. Reflection of light by the well and the adhesive provides more efficient light output than would otherwise be achieved. Connection blocks  909   a  and  909   b  are provided for forming electrical connection with diodes  910   a  and  910   b.  A focus dome, lens, or cover  910  is provided that is transparent to the light being emitted. The focus dome may have the characteristic of serving to focus light being emitted from the chips in order to create a substantially coherent beam of usable light. 
     FIG. 10  depicts a light source of the invention  1001  having an LED or laser light source  1002  located in an enclosure  1003 . The enclosure may be any appropriate shape. The depicted shape is that of a bulb, but flat, arcuate, rounded or other shapes may be used depending on the application. The enclosure  1003  may be glass, plastic, polycarbonate or any other material that is substantially transparent to the light to be emitted. The enclosure  1003  has an exterior surface  1003   a  and an interior surface  1003   b.  The enclosure serves as a protector of the light source  1002  and it may be designed to diffuse light. The interior surface  1003   b  of the enclosure may have a coating or layer  1004  which serves to alter properties of the light emitted from the light source  1002 . For example, if light from the light source  1002  is single wavelength, then the light-altering coating  1004  may be phosphorous which will turn the monochromatic light into white light. Other coatings may be used as desired to alter the light in other ways. 
     FIG. 11  depicts a power supply module  701  for a light source of the invention. The power supply module  701  includes a fitting or connector  702  with electrodes  703  and  704  for receiving AC electrical input from a traditional light bulb socket. An AC/DC converter  705  is provided to convert AC power from standard building wiring into DC power usable by the semiconductor chips of the invention. Electrical lead wires  706   a  and  706   b  are provided for electrical connection to the chips to power the light source, and electrical lead wires  707   a  and  707   b  are provided to provide power for the cooling fan TE cooler. The coating may be applied on the interior or exterior of the enclosure, or both. 
   Examples of some heat sink materials which may be used in the invention include copper, aluminum, silicon carbide, boron nitride natural diamond, monocrystalline diamond, polycrystalline diamond, polycrystalline diamond compacts, diamond deposited through chemical vapor deposition and diamond deposited through physical vapor deposition. Any materials with adequate heat conductance can be used. 
   Examples of heat conductive adhesives which may be used are silver based epoxy, other epoxies, and other adhesives with a heat conductive quality. In order to perform a heat conductive function, it is important that the adhesive possess the following characteristics: (i) strong bonding between the materials being bonded, (ii) adequate heat conductance, (iii) electrically insulative or electrically conductive as desired, and (iv) light reflective as desired. Examples of light reflective adhesives which may be used include silver and aluminum based epoxy. 
   Examples of substrates on which the semiconductors used in the invention may be grown include Si, GaAs, GaN, InP, sapphire, SiC, GaSb, InAs and others. These may be used for both electrically insulative and electrically conductive substrates. 
   Materials which may be used to used as a thermoelectric cooler in the invention include known semiconductor junction devices. 
   It will be preferred that the semiconductor light source of the invention will emit light in the wavelength range of 200 to 700 in order to be useful for illumination of a physical space used by humans. 
   Heat sinks used in this invention can be of a variety of shapes and dimensions, such as those depicted in the drawings or any others which are useful for the structure of the particular light source being constructed. 
   Any of the foregoing, including combinations thereof, and other semiconductors, materials and components may be used in the invented light sources. 
   While the present invention has been described and illustrated in conjunction with a number of specific embodiments, those skilled in the art will appreciate that variations and modifications may be made without departing from the principles of the invention as herein illustrated, as described and claimed. The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are considered in all respects to be illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims, rather than by the foregoing description. All changes which come within the meaning and range of equivalence of the claims are to be embraced within their scope.