Light-Emitting Devices Based on Gallium Nitride and Related Compound Semiconductors

ABSTRACTAsymmetric double heterostructures (ADH) of AlGaN/GaInN/GaN blue light emitting diodes (LEDs) and GaInN/GaN multiple quantum well (MQW) LEDs were fabricated by metalorganic vapor phase epitaxy (MOVPE). The ADH LEDs had spectral emissions peaking at 450 nm and the luminous intensify was 2.5 cd at 20 mA The output power was 3.6 mW at 20mA and the external quantum efficiency was as high as 5.1 % at 20 mA. The GaInN/GaN MQW structure was grown successfully by MOVPE. Fine multi-layer structures 7 – 9 nm thick were detected by secondary ion mass spectroscopy and transmission electron microscopy (TEM). The dislocation density in the MQW was as high as 0.5–2×109 cm−2 by TEM The optical efficiency of the MQW layer was higher than that of a bulk GalnN layer. The intensity of UV emission from MQW LEDs was greater than that of blue light from ADH blue LEDs. The UV emission increased as a super-linear function of injection current at -100°C.