Light emitting diode with light conversion by dielectric phosphor powder

Abstract

The invention provides a light emitting diode (LED) comprising a light emitting component and dielectric phosphor powder (DPP) which absorb a part of light emitted by the light emitting component and emits light of a wavelength that is different from that of the absorbed light. In a preferred embodiment according to the invention, the LED includes a crystalline semiconductor chip serving as the light emitting component. The dielectric phosphor powder is made of a mixture of phosphor particles and microscopic, nearly spherical dielectric particles with a band gap larger than 3 eV (which do not absorb blue light in the spectrum). The DPP can also include phosphor particles, and bubbles (or voids) instead of the dielectric particles. The bubbles of the DPP have a band gap larger than 3 eV which do not absorb blue light in the spectrum. The bubbles can be air bubbles, N2 bubbles, noble gas bubbles. Furthermore, the DPP can also be a mixture of the bubbles, dielectric particles, and the phosphor particles. According to another embodiment, the invention provides a light emitting diode (LED) comprising a light emitting component (such as a crystalline semiconductor chip) and dielectric phosphor powder (DPP) made of a mixture of crystalline phosphor particles and microscopic, nearly spherical dielectric particles. According to yet another embodiment, the invention provides a light emitting diode (LED) comprising a light emitting component (such as an AlInGaN crystalline semiconductor chip) encapsulated into dielectric phosphor powder (DPP). The DPP is made of a mixture of microscopic, nearly spherical dielectric particles of microcrystalline AlN. The LED according to this particular embodiment can also be a white LED. An exemplary structure of an LED according to a preferred embodiment of the invention comprises a crystalline semiconductor chip encapsulated into epoxy, wires connected to the semiconductor chip, metallic leads connected to the wires, and an epoxy encapsulation covered with dielectric phosphor powder (DPP). The DPP is made of a mixture of nearly spherical dielectric particles with crystalline phosphor particles embedded into the epoxy.

We claim:  
     
         1 . A light emitting diode (LED) comprising: 
 a light emitting component emitting a light; and    a dielectric phosphor powder (DPP) which absorbs a part of the light emitted by the light emitting component and emits light of a wavelength that is different from that of the absorbed light;    wherein the dielectric phosphor powder (DPP) is made of a mixture of crystalline phosphor particles and microscopic, nearly spherical dielectric particles.    
     
     
         2 . The LED of  claim 1  wherein concentration of the phosphor particles are generally 2% to 25% of total volume of the dielectric phosphor powder (DPP).  
     
     
         3 . The LED of  claim 1  wherein the light emitting component is one selected from the group consisting of a crystalline semiconductor chip, nitride compound semiconductor chip, a gallium nitride compound semiconductor, InGaN crystalline semiconductor chip, and AlInGaN crystalline semiconductor chip.  
     
     
         4 . The LED of  claim 1  wherein the light emitted by the dielectric phosphor powder (DPP) is a white light.  
     
     
         5 . The LED of  claim 1  wherein the dielectric particles have a band gap larger then 3 eV.  
     
     
         6 . The LED of  claim 1  wherein the dielectric particles do not absorb blue light.  
     
     
         7 . The LED of  claim 1  wherein the dielectric particles are selected from the group consisting of microcrystalline AlN, amorphous Si 3 N 4 , amorphous GaN, and amorphous SiO 2 .  
     
     
         8 . The LED of  claim 1  wherein the dielectric particles are selected from the group consisting of amorphous Si 3 N 4  with radii generally between 50 and 5000 nm, amorphous SiO 2  with radii generally between 50 and 5000 nm, and amorphous GaN with radii generally between 50 and 5000 nm.  
     
     
         9 . The LED of  claim 1  wherein the phosphor particles are micro-crystals of a garnet fluorescent material with radii generally between 1000 and 10,000 nm.  
     
     
         10 . The LED of  claim 1  wherein the phosphor particles are selected from the group consisting of Gd, Y, Ce and Nd-based phosphors.  
     
     
         11 . The LED of  claim 1  wherein the phosphor particles include phosphors of garnet fluorescent material activated with cerium containing at least one element selected from the group consisting of Y, Lu, Sc, La, Gd and Sm, and at least one element selected from another group consisting of Al, Ga and In.  
     
     
         12 . The LED of  claim 1  wherein the mixture of the DPP further comprises bubbles having a band gap larger than 3 eV.  
     
     
         13 . The LED of  claim 12  wherein the mixture of the DPP further comprises bubbles which do not absorb blue light.  
     
     
         14 . The LED of  claim 1  wherein the mixture of the DPP further comprises voids selected from the group consisting of air bubbles, N2 bubbles, and noble gas bubbles.  
     
     
         15 . A light emitting diode (LED) comprising: 
 a light emitting component emitting a light; and    a dielectric phosphor powder (DPP) which absorbs a part of the light emitted by the light emitting component and emits light of a wavelength that is different from that of the absorbed light;    wherein the dielectric phosphor powder (DPP) is made of a mixture of crystalline phosphor particles and light scattering media particles wherein the light scattering media particles have a band gap larger than 3 eV.    
     
     
         16 . The LED of  claim 15  wherein the media particles do not absorb blue light.  
     
     
         17 . The LED of  claim 15  wherein the media particles are dielectric particles.  
     
     
         18 . The LED of  claim 15  wherein concentration of the phosphor particles are generally 2% to 25% of total volume of the dielectric phosphor powder (DPP).  
     
     
         19 . The LED of  claim 15  wherein the light emitting component is one selected from the group consisting of a crystalline semiconductor chip, nitride compound semiconductor chip, a gallium nitride compound semiconductor, InGaN crystalline semiconductor chip, and AlInGaN crystalline semiconductor chip.  
     
     
         20 . The LED of  claim 15  wherein the light emitted by the dielectric phosphor powder (DPP) is a white light.  
     
     
         21 . The LED of  claim 15  wherein the light scattering media particles are selected from the group consisting of microcrystalline AlN, amorphous Si 3 N 4 , amorphous GaN, and amorphous SiO 2 .  
     
     
         22 . The LED of  claim 15  wherein the light scattering media particles are selected from the group consisting of amorphous Si 3 N 4  with radii generally between 50 and 5000 nm, amorphous SiO 2  with radii generally between 50 and 5000 nm, and amorphous GaN with radii generally between 50 and 5000 nm.  
     
     
         23 . The LED of  claim 15  wherein the phosphor particles are micro-crystals of a garnet fluorescent material with radii generally between 1000 and 10,000 nm.  
     
     
         24 . The LED of  claim 15  wherein the phosphor particles are selected from the group consisting of Gd, Y, Ce and Nd-based phosphors.  
     
     
         25 . The LED of  claim 15  wherein the phosphor particles include phosphors of garnet fluorescent material activated with cerium containing at least one element selected from the group consisting of Y, Lu, Sc, La, Gd and Sm, and at least one element selected from another group consisting of Al, Ga and In.  
     
     
         26 . The LED of  claim 15  wherein the mixture of the DPP further comprises bubbles having a band gap larger than 3 eV.  
     
     
         27 . The LED of  claim 26  wherein the mixture of the DPP further comprises bubbles which do not absorb blue light.  
     
     
         28 . The LED of  claim 15  wherein the mixture of the DPP further comprises voids selected from the group consisting of air bubbles, N2 bubbles, and noble gas bubbles.  
     
     
         29 . The LED of  claim 15  wherein the light scattering media particles include voids wherein the voids are selected from the group consisting of air bubbles, N2 bubbles, and noble gas bubbles.  
     
     
         30 . The LED of  claim 29  wherein the bubbles do not absorb blue light.  
     
     
         31 . The LED of  claim 15  further comprising: 
 a crystalline semiconductor chip wherein the crystalline phosphor particles are embedded into epoxy;  
 wires connected to the semiconductor chip;  
 metallic leads connected to the wires for transferring an electrical current to the semiconductor chip; and  
 an epoxy encapsulation covered with the dielectric phosphor powder (DPP).  
 
     
     
         32 . The LED of  claim 15  further comprising: 
 a crystalline semiconductor chip encapsulated into the dielectric phosphor powder (DPP) wherein the crystalline phosphor particles are embedded into epoxy;  
 wires connected to the semiconductor chip;  
 metallic leads connected to the wires for transferring an electrical current to the semiconductor chip; and  
 an epoxy encapsulation covered with the dielectric phosphor powder (DPP).  
 
     
     
         33 . A light emitting diode (LED) comprising: 
 a crystalline semiconductor chip;    a dielectric phosphor powder (DPP) made of a mixture of microscopic, nearly spherical dielectric particles with crystalline phosphor particles embedded into epoxy;    wires connected to the semiconductor chip;    metallic leads connected to the wires for transferring an electrical current to the semiconductor chip; and    an epoxy encapsulation covered with the dielectric phosphor powder (DPP).    
     
     
         34 . The LED of  claim 33  wherein concentration of the phosphor particles are generally 2% to 25% of total volume of the dielectric phosphor powder (DPP).  
     
     
         35 . The LED of  claim 33  wherein the semiconductor chip is one selected from the group consisting of a nitride compound semiconductor chip, a gallium nitride compound semiconductor, InGaN crystalline semiconductor chip, and AlInGaN crystalline semiconductor chip.  
     
     
         36 . The LED of  claim 33  wherein the light emitted by the dielectric phosphor powder (DPP) is a white light.  
     
     
         37 . The LED of  claim 33  wherein the dielectric particles have a band gap larger then 3 eV.  
     
     
         38 . The LED of  claim 33  wherein the dielectric particles do not absorb blue light.  
     
     
         39 . The LED of  claim 33  wherein the dielectric particles are selected from the group consisting of microcrystalline AlN, amorphous Si 3 N 4 , amorphous GaN, and amorphous SiO 2 .  
     
     
         40 . The LED of  claim 33  wherein the dielectric particles are selected from the group consisting of amorphous Si 3 N 4  with radii generally between 50 and 5000 nm, amorphous SiO 2  with radii generally between 50 and 5000 nm, and amorphous GaN with radii generally between 50 and 5000 nm.  
     
     
         41 . The LED of  claim 33  wherein the phosphor particles are micro-crystals of a garnet fluorescent material with radii generally between 1000 and 10,000 nm.  
     
     
         42 . The LED of  claim 33  wherein the phosphor particles are selected from the group consisting of Gd, Y, Ce and Nd-based phosphors.  
     
     
         43 . The LED of  claim 33  wherein the phosphor particles include phosphors of garnet fluorescent material activated with cerium containing at least one element selected from the group consisting of Y, Lu, Sc, La, Gd and Sm, and at least one element selected from another group consisting of Al, Ga and In.  
     
     
         44 . The LED of  claim 33  wherein the mixture of the DPP further comprises bubbles having a band gap larger than 3 eV.  
     
     
         45 . The LED of  claim 44  wherein the mixture of the DPP further comprises bubbles which do not absorb blue light.  
     
     
         46 . The LED of  claim 33  wherein the mixture of the DPP further comprises voids selected from the group consisting of air bubbles, N2 bubbles, and noble gas bubbles.  
     
     
         47 . A light emitting diode (LED) comprising: 
 a crystalline semiconductor chip encapsulated into a dielectric phosphor powder (DPP) made of a mixture of microscopic, nearly spherical dielectric particles with crystalline phosphor particles embedded into epoxy;    wires connected to the semiconductor chip;    metallic leads connected to the wires for transferring an electrical current to the semiconductor chip; and    an epoxy encapsulation covered with the dielectric phosphor powder (DPP).    
     
     
         48 . The LED of  claim 47  wherein concentration of the phosphor particles are generally 2% to 25% of total volume of the dielectric phosphor powder (DPP).  
     
     
         49 . The LED of  claim 47  wherein the semiconductor chip is one selected from the group consisting of a nitride compound semiconductor chip, a gallium nitride compound semiconductor, InGaN crystalline semiconductor chip, and AlInGaN crystalline semiconductor chip.  
     
     
         50 . The LED of  claim 47  wherein the light emitted by the dielectric phosphor powder (DPP) is a white light.  
     
     
         51 . The LED of  claim 47  wherein the dielectric particles have a band gap larger then 3 eV.  
     
     
         52 . The LED of  claim 47  wherein the dielectric particles do not absorb blue light.  
     
     
         53 . The LED of  claim 47  wherein the dielectric particles are selected from the group consisting of microcrystalline AIN, amorphous Si 3 N 4 , amorphous GaN, and amorphous SiO 2 .  
     
     
         54 . The LED of  claim 47  wherein the dielectric particles are selected from the group consisting of amorphous Si 3 N 4  with radii generally between 50 and 5000 nm, amorphous SiO 2  with radii generally between 50 and 5000 nm, and amorphous GaN with radii generally between 50 and 5000 nm.  
     
     
         55 . The LED of  claim 47  wherein the phosphor particles are micro-crystals of a garnet fluorescent material with radii generally between 1000 and 10,000 nm.  
     
     
         56 . The LED of  claim 47  wherein the phosphor particles are selected from the group consisting of Gd, Y, Ce and Nd-based phosphors.  
     
     
         57 . The LED of  claim 47  wherein the phosphor particles include phosphors of garnet fluorescent material activated with cerium containing at least one element selected from the group consisting of Y, Lu, Sc, La, Gd and Sm, and at least one element selected from another group consisting of Al, Ga and In.  
     
     
         58 . The LED of  claim 47  wherein the mixture of the DPP further comprises bubbles having a band gap larger than 3 eV.  
     
     
         59 . The LED of  claim 58  wherein the mixture of the DPP further comprises bubbles which do not absorb blue light.  
     
     
         60 . The LED of  claim 47  wherein the mixture of the DPP further comprises voids selected from the group consisting of air bubbles, N2 bubbles, and noble gas bubbles.  
     
     
         61 . A light emitting diode (LED) comprising: 
 a light emitting component emitting a light; and    a mixture of phosphor particles and voids wherein the mixture absorbs a part of the light emitted by the light emitting component and emits light of a wavelength that is different from that of the absorbed light.    
     
     
         62 . The LED of  claim 61  wherein the voids are selected from the group consisting of air bubbles, N2 bubbles, and noble gas bubbles.  
     
     
         63 . The LED of  claim 61  wherein the voids have a band gap larger than 3 eV.  
     
     
         64 . The LED of  claim 61  wherein the voids do not absorb blue light.  
     
     
         65 . The LED of  claim 61  further comprising: 
 a crystalline semiconductor chip wherein the phosphor particles are embedded into epoxy;  
 wires connected to the semiconductor chip;  
 metallic leads connected to the wires for transferring an electrical current to the semiconductor chip; and  
 an epoxy encapsulation covered with the mixture.  
 
     
     
         66 . The LED of  claim 61  further comprising: 
 a crystalline semiconductor chip encapsulated into the mixture wherein the phosphor particles are embedded into epoxy;  
 wires connected to the semiconductor chip;  
 metallic leads connected to the wires for transferring an electrical current to the semiconductor chip; and  
 an epoxy encapsulation covered with the mixture.