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).

The use of planar and axial channeling to measure the magnitude of the tetragonal distortion (and hence the strain) in simple strained-layer systems has been investigated. The test structures consisted of a 250 Å epitaxial InxGa1−xAs layer sandwiched between a (100) GaAs substrate and a thin (250–360 Å) surface GaAs epilayer. The In concentrations were sufficiently high (0.10–0.16) so that the resulting tilt or kink angle, Δ, at the buried interface exceeded the planar critical angle ψc for the 2.0 MeV4He+ beam. Complications in the observed axial and planar angular scans in the InGaAs layer have been studied in detail and suitable methods for extracting the correct values of Δ have been established. Planar channeling measurements, corrected for specular reflection effects in the GaAs surface layer, give Δ values in very good agreement with those calculated from the indium content. Axial channeling, however, can only be used to determine Δ when the surface GaAs overlayer is thinner than d/ψc, where d is the spacing between atomic strings.

The enhancement in ion backscattering surface peak yield at 180° has been measured for 0.5 MeV and 1.0 MeV He+ incident upon the 〈110〉 and 〈112〉 directions of a near (110)Au single crystal at 40 K, 170 K, and 300 K. The normal (RBS) surface peak yield observed at 150° is in agreement with that calculated by computer simulation using a modified 1 × 2 surface structure for (110)Au, including the effects of enhanced vibrations in the surface layers and vibration correlations. A theoretical description of the enhanced yield at 180°, based on a two-atom scattering model, is given. The theoretical enhancement from a 1 × 2 surface is in good agreement with the observations.