Composition studies of MBE GaInP alloys by Rutherford scattering and x-ray diffraction

Abstract

Layers of Ga_x In_1−x P (x?0.5) have been grown by molecular‐beam epitaxy on GaAs substrates, and their composition measured by both x‐ray determination of the lattice parameter and high‐energy Rutherford scattering. The x‐ray data were corrected for elastic strain due to mismatch and backscattering spectra were analyzed with the aid of computer simulation. Assuming a linear relation between lattice parameter and composition, values of x obtained from these two techniques agreed within experimental error (∼1%). Backscattering results for layer thickness were within 2% of results from ir interference. Small composition variations across the layers were detected by both techniques, and these can be accounted for by the geometry of the cells in the growth chamber. Rutherford scattering has also been used to assess the depth uniformity of composition and analyze GaInP/GaAs/GaInP heterostructures with total thickness ∼2 μm.