Light emitting diode with light conversion using scattering optical media

Abstract

The invention provides a light emitting diode (LED) or other light emitting means such as a laser diode (LD) comprising a light emitting component and scattering optical media such as 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 scattering optical media such as dielectric phosphor powder (DPP) 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 scattering optical media such as 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 scattering optical media such as 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 scattering optical media such as 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 scattering optical media such as 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 scattering optical media such as dielectric phosphor powder (DPP). The DPP is made of a mixture of nearly spherical dielectric particles with crystalline phosphor particles embedded into the epoxy.