Structural properties of wurtzitelike ScGaN films grown by NH3-molecular beam epitaxy

Moram, M A and Zhang, Y and Joyce, T B and Holec, D and Chalker, P R and Mayrhofer, P H and Kappers, M J and Humphreys, C J


Scandium gallium nitride(ScxGa1−xN) alloy films with low Sc concentrations (up to approximately x=0.08) were grown using molecular beam epitaxy with NH3 as a reactive N source, on GaNfilms that were grown on sapphire using metalorganic vapor phase epitaxy(MOVPE). High-resolution x-ray diffraction and transmission electron microscopy revealed that both the c and the alattice parameters increased with increasing Sc concentration, as predicted for a wurtzite-structure alloy. As the Sc content increased, the relaxation of the compressive stress in the ScxGa1−xNfilms occurred mainly via the introduction of additional a-type dislocations, but neither stacking faults nor significant compositional segregation was observed at any composition. A dewetting effect (which increased with increasing Sc content) was observed in MOVPE-grown GaN deposited on top of the ScxGa1−xNfilms, but the ScxGa1−xN remained compositionally and structurally stable under GaNgrowth conditions.

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