Electrode structures for LEDs with increased active area
View Patent ↗An electrode structure is disclosed for enhancing the brightness and/or efficiency of an LED. The electrode structure can have a metal electrode and an optically transmissive thick dielectric material formed intermediate the electrode and a light emitting semiconductor material. The electrode and the thick dielectric cooperate to reflect light from the semiconductor material back into the semiconductor so as to enhance the likelihood of the light ultimately being transmitted from the semiconductor material. Such LED can have enhanced utility and can be suitable for uses such as general illumination. The semiconductor material can have a cutout formed therein and a portion of the electrode can be formed outside of the cutout and a portion of the electrode can be formed inside of the cutout. The portion of the electrode outside the cutout can be electrically isolated from the semiconductor material by the dielectric material.
1. An electrode structure, the electrode structure comprising: a semiconductor material having a cutout formed therein, the semiconductor material defining a portion of an LED; an electrically insulating dielectric material; and a metal electrode; wherein a portion of the electrode is formed outside of the cutout and a portion of the same electrode is formed inside of the cutout; wherein the portion of the electrode outside the cutout is separated from the semiconductor material by the dielectric material; wherein the portion of the electrode inside the cutout is in electrical contact with the semiconductor material and wherein the dielectric material is optically transmissive, having an index of refraction greater than or equal to one and less than that of a semiconductor upon which the dielectric material is formed, and having a thickness greater than ½λ, where λ is a wavelength of light generated by the LED; the dielectric material being formed to the electrode so as to enhance reflection of light.
2. The electrode structure as recited in claim 1 , further comprising:
at least one pair of dielectric layers configured so as to define a DBR structure and disposed between the a portion of the electrode and a portion of the dielectric; and
wherein each pair of dielectric layers is substantially optically transmissive, is comprised of layers of materials of different indices of refraction, and is a multiple of approximately ¼λ thick.
3. An electrode structure, the electrode structure comprising: a semiconductor material having a cutout formed therein, the semiconductor material defining a portion of an LED; an electrically insulating dielectric material; and a metal electrode; wherein a portion of the electrode is formed outside of the cutout and a portion of the same electrode is formed inside of the cutout; wherein the portion of the electrode outside the cutout is separated from the semiconductor material by the dielectric material; wherein the portion of the electrode inside the cutout is in electrical contact with the semiconductor material and wherein the dielectric material has a thickness of approximately 1.75λ, where λ is a wavelength of light generated by the LED.