Ion-channeling studies of In yGa 1−yAs/GaAs strained-layer single and multiple quantum-well structures

Abstract

Dechanneling and angular scan measurements with 2 MeV 4He + ions have been performed to investigate molecular-beam epitaxially (MBE)-grown strained In yGa 1− yAs/GaAs single quantum well (SQW) and multiple quantum well (MQW) structures grown on (100) GaAs substrates. Dechanneling analysis was carried out in the 〈100〉 direction and in the (011) and (0 1 1) planes in order to determine defect densities. Since the defect densities were near the detection limit of Rutherford backscattering (RBS), it was necessary to optimize all measurement conditions. Ion channeling angular scans about the 〈110〉 axis were carried out in the (001) plane. In both SQW and MQW structures, the angular difference between the 〈110〉 directions of the substrate and the In yGa 1− yAs epilayers (kink angle) was determined from the experimental data. The kink angles of the MQW targets determined by RBS are consistent with the kink angles determined by X-ray diffraction (XRD). The indium concentrations calculated from the kink angles, assuming fully commensurate growth, are lower than expected and differ from the results obtained by photoluminescence (PL).