Heteroepitaxial growth of III–V compound semiconductors for optoelectronic devices

An AlGaAs/GaAs multi-quantum well vertical-cavity surface-emitting laser diode (VCSELD) has been grown on a Si substrate using metalorganic chemical vapour deposition (MOCVD). The VCSELD with a 23-pair of AlAs/Al0·1Ga0·9As distributed Bragg reflector on a Si substrate exhibited a threshold current of 223 mA under continuous-wave condition at 220 K. Electroluminescence observation showed that an optical degradation was caused by generation and growth of dark-line defects. An MOCVD-grown InGaN/AlGaN double-heterostructure light-emitting diode on a sapphire substrate exhibited an optical output power of 0·17 mW, an external quantum efficiency of 0·2%, a peak emission wavelength at 440 nm with a full width at half-maximum of 63 nm and a stable operation up to 3000 h under 30 mA DC operation at 30°C. A high current level of 281 mA/mm and a large transconductance (gm) of 33 mS/mm have been achieved for a GaN metal semiconductor field-effect transistor (MESFET) with a gate length of 2 µm and a width of 200 µm at 25°C. The GaN MESFET at 400°C showed degraded characteristics: a lowgm of 13·4 mS/mm, a gate leakage and a poor pinch-off.