Entropy-driven stabilization of a novel configuration for acceptor-hydrogen complexes in GaN.
We present a model for the microscopic structure of Mg-H complexes in GaN, explaining the unusual bond angle observed in recent vibrational spectroscopy studies. The structure is not the lowest-energy configuration at T = 0, but it is stabilized at elevated temperatures due to the large entropy associated with a set of low-energy rotational excitations. The rotational excitation spectrum is calculated using a quantum-mechanical model in which the hydrogen atom moves in a weak corrugation potential. Consequences for experiment are discussed.
Limpijumnong
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Xerox Palo Alto Research Center, 3333 Coyote Hill Road, Palo Alto, California 94304.
Northrup
J E
JE
Van De Walle
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CG