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Doping Issues in Wide Band-Gap SemiconductorsExeter, United Kingdom21-23 March 2001 |
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The problem of beryllium doping in gallium nitride has been investigated using the AIMPRO local-density-functional theory based method. Three defects are considered: substitional beryllium acceptors, interstitial beryllium atoms, and a beryllium pair near to a vacant gallium lattice site. The formation energy of a neutral Be acceptor is found to be approximately 2.4 eV, in good agreement with the value of 2.2 eV calculated earlier by Neugebauer and Van de Walle.[1] Interstitial Be lies very close to the hexagonal site on a nitrogen plane. The substitutional-interstitial pair is very strongly bound with an energy of approximately 4.2 eV. It is a deep donor; thus its formation provides a possible explaination the poor doping efficiency of Be in GaN.
[1] J. Neugebauer and C. G. Van de Walle, J. Appl. Phys., 85, 3003-3005 (1999)