Planar channeling in GaAs/In x Ga1− x As/GaAs strained-layer structures

Planar {110} channeling measurements with 1–2-MeV He+ ions have been used to investigate strained-layer structures of (100) GaAs/InxGa1−xAs/GaAs with x=0.07–0.17. Beam-steering effects in the surface GaAs layer are observed to have a major influence on {110} planar angular scans carried out in the InxGa1−xAs layers resulting generally in a double or more complex-shaped angular dip. A simple computer simulation has been developed which determines the main features of the experimental angular scan data. Comparison of simulation and experimental data allows a reasonable determination of the kink angle θK between the {110} planes for the surface GaAs and underlying strained layer. Only in limiting cases is it possible to unequivocally determine θK from the experimental data alone. They are as follows: (i) when θK=0; (ii) θK>2ψ pc (ψ pc is the critical angle for {110} planar channeling); and (iii) when the thickness t of the top layer is thin (t≪2d/ψ pc, where d is the {110} interplanar spacing).