Ab initio cluster calculations of hydrogenated GaAs„001... surfaces
نویسندگان
چکیده
Hydrogen adsorption on the ~234! and ~432! reconstructions of gallium arsenide ~001! has been studied by internal reflectance infrared spectroscopy and ab initio cluster calculations with density-functional theory. The calculations are made on Ga5As4H11,13, Ga4As5H11,13 , and Ga7As8H19 clusters, which model the arsenicand gallium-dimer termination of the semiconductor surface. Excellent agreement has been achieved between the vibrational frequencies predicted by the theory and those observed in experiments. On the ~234!, hydrogen adsorbs on arsenic dimers to form isolated and coupled arsenic-monohydrogen bonds, and arsenic-dihydrogen bonds. Conversely, on the ~432!, hydrogen adsorbs on gallium dimers to form terminal and bridged gallium hydrides. The latter species occur in isolated or coupled structures involving two or three Ga atoms.
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