GaN/AIN multiple quantum wells grown on GaN-AIN waveguide structure by metalorganic vapor-phase epitaxy

Abstract

High-optical-confinement waveguide structure based on nitride semiconductors is proposed and demonstrated for the first time with metal organic vaporphase epitaxy. The waveguide structure composed of 1-µm-thick AIN cladding layer, 2-µm-thick GaN guiding layer, and 40 periods of GaN/AIN multiple quantum wells (MQWs) was grown using optimized growth conditions for each layer. For improved material quality, the two-step growth technique using low-temperature AIN and GaN nucleation layers was utilized to reduce the stress induced by lattice mismatch between each layer. The high-optical-confinement structure could therefore be grown with high quality, leading to a successful observation of inter-sub-band absorption in GaN/AIN MQWs. The inter-sub-band absorption wavelength observed in such structure is in good agreement with that of MQWs grown on GaN layer, showing that the proposed waveguide structure can be used as a standard structure for optical devices based on inter-sub-band absorption.