Abstract: A nitride light emitting diode is fabricated on a transparent sapphire substrate. The LED is then mounted upside-down on a conductive silicon substrate with a bottom electrode to serve as the output terminal for the cathode of the LED. The LED die is partially etched to expose the anode of the LED, where a top electrode is formed. In comparison with conventional LED structure with both electrodes located on top of the die, moving one electrode to the bottom allows more light to be transmitted upward and reflects the light incident downward. For equal amount of light emission, the new structure occupies less area.

Abstract: A transparent conductive layer is deposited between the electrode and the semiconductor diode to spread the current evenly to the diode and to reduce the series resistance. Tin indium oxide can be used as the transparent conductive layer. The transparent conductive layer is particularly applicable to a blue light emitting diode, where InGaN is used as the light emitting layer.

Abstract: A high bandgap material is used as a cladding layer to confine the carrier overflow in a aluminum-gallium-indium-phosphide light emitting diode. The quantum efficiency is improved. The use of this high bandgap material as a window material also prevents current crowding. The efficiency can further be improved by using a Distributed Bragg Reflector in the structure to reflect light, and a buffer layer to reduce interface dislocation.