ION-CHANNELING STUDIES OF INYGA1-YAS GAAS STRAINED-LAYER SINGLE AND MULTIPLE-QUANTUM-WELL STRUCTURES/

Dechanneling and angular scan measurements with 2 MeV He-4(+) ions hav e been performed to investigate molecular-beam epitaxially (MBE)-grown strained InyGa1-yAs/GaAs single quantum well (SQW) and multiple quant um well (MQW) structures grown on (100) GaAs substrates. Dechanneling analysis was carried out in the (100) direction and in the (011) and ( 0 $($) over bar$$ 11) planes in order to determine defect densities. S ince the defect densities were near the detection limit of Rutherford backscattering (RBS), it was necessary to optimize all measurement con ditions. Ion channeling angular scans about the (110) axis were carrie d out in the (001) plane. In both SQW and MQW structures, the angular difference between the (110) directions of the substrate and the InyGa 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 commen surate growth, are lower than expected and differ from the results obt ained by photoluminescence (PL).