Tetragonal distortion of InAsPSb film grown on InAs substrate studied by Rutherford backscattering/channeling and synchrotron X-ray diffraction

Abstract Rutherford backscattering/channeling spectrometry and synchrotron X-ray diffraction are employed to characterize the structural properties of the InAsPSb epilayer grown on the InAs substrate. The results indicate that a 975-nm thick InAs 0.668 P 0.219 Sb 0.113 layer has a quite good crystalline quality ( χ min =6.1%). The channeling angular scan around an off-normal 〈1 1 1〉 axis in the (0 1 1) plane of the sample is used to determine the tetragonal distortion e T , which is caused by elastic strain in the layer. The results show that the InAsPSb layer is subjected to an elastic strain at the interfacial layer, and the strain decreases gradually moving towards the near-surface layer. It is expected that an epitaxial InAsPSb layer with the thickness of around 1700 nm will be fully relaxed ( e T =0). The magnitude difference of e T deduced from angular scans and X-ray diffraction implies some structure (like dislocations) may play a role.