Composition measurement of epitaxial xGa1−xN films

Tsui, H C L and Goff, L E and Barradas, N P and Alves, E and Pereira, S and Palgrave, R G and Davies, R J and Beere, H E and Farrer, I and Ritchie, D A and Moram, M A


Four different methods for measuring the compositions of epitaxial xGa1−xN films were assessed and compared to determine which was the most reliable and accurate. The compositions of epitaxial ScxGa1−xN films with 0 ≤ x ≤ 0.26 were measured directly using Rutherford backscattering (RBS) and X-ray photoelectron spectroscopy (XPS), and indirectly using c lattice parameter measurements from x-ray diffraction and c / a ratio measurements from electron diffraction patterns. RBS measurements were taken as a standard reference. XPS was found to underestimate the Sc content, whereas c lattice parameter and c / a ratio were not reliable for composition determination due to the unknown degree of strain relaxation in the film. However, the Sc flux used during growth was found to relate linearly with x and could be used to estimate the Sc content.

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Department of Materials
Imperial College London
Royal School of Mines
Exhibition Road
London, SW7 2AZ - UK