Epitaxial growth of rhombohedral boron phosphide single crystalline films by chemical vapor deposition

Rhombohedral boron phosphide (B12P2) single crystalline films were grown at 1100 degrees C by thermal decomposition of a B2H6-PH3-H-2 gas mixture. The crystal quality and orientation of the films, determined by reflection high-energy electron diffraction and X-ray diffraction, are strongly influenced by the flow rates of reactant gases, The epitaxial relationships are B12P2 (11 (2) over bar 0)[0001] parallel to Si (100)[010],[011] and B12P2 (10 (1) over bar 1)[1 (2) over bar 10], [10 (1) over bar 4] parallel to Si (100)[010], of eight- and twofold symmetry, respectively, The distribution of the two planes in the films changes along the growth direction, The epitaxial relationship on the Si (111) surface is B12P2 (1010)[0001] parallel to Si (111)[110]. The B12P2 (02 (2) over bar 1) plane grows near the substrate, but the existence of the (10 (1) over bar 0) plane increases during the crystal growth process. The optimum flow rates of B2H6 and PH3 are 30 sccm for the best epitaxy, which occurs far the lowest mismatch. (C) 1997 Academic Press.