Fabrication of InGaN/GaN multiple quantum wells on (1-101) GaN

InGaN/GaN multiple quantum wells (MQWs) on semipolar (1-101) GaN microstripes on a Si substrate were fabricated and their optical properties were investigated. From cathodoluminescence (CL) analysis, strong CL emission was obtained in an MQW emitting at 433 nm. However, dark lines appeared in MQWs emitting at longer wavelengths. These dark lines are attributed to lattice relaxation and the generation of misfit dislocations and stacking faults in an MQW, resulting in nonradiative centers. The internal quantum efficiency (IQE) was estimated from excitation-power-dependent photoluminescence analysis. The (1-101) InGaN/GaN MQW had a high IQE owing to the high crystalline quality of the underlying GaN and the reduced piezoelectric field. The IQE at a carrier concentration of 1 × 1018 cm-3 in a sample emitting at 490nm was as high as 90%. The efficiency decreased in a sample with a higher indium content in the MQW due to the generation of misfit dislocations and stacking faults.