Monolithic white light emitting diodes based on InGaN/GaN multiple-quantumwells

Light emitting diodes (LEDs) based on In(x)Gal(1-x)N (x = 0.15-0.2)/GaN mul tiple-quantum wells ( MQWs) have been grown on sapphire substrates. Their w avelength emission can be tuned from blue to orange by increasing the QW th ickness. This opens the way for monolithic white LEDs by combining several QWs of various thicknesses, i.e., "colors", inside the GaN p-n junction. Th is is demonstrated by the realization of white (blue + yellow) dual color L EDs. The coordinates in the CIE 1931 chromaticity diagram of the EL spectru m are (x = 0.29, y = 0.31) and correspond to a color temperature of 8000 K. The expected performances of the monolithic white LEDs are compared to hyb rid technologies such as blue LEDs pumping yellow phosphors.