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1994
Journal Article
Titel
Bonding of H-CAs pairs in Al(x)Ga(1-x)As alloys
Alternative
Bindung von H-CAs Paaren in Al(x)Ga(1-x)As Legierungen
Abstract
The local structure of C As acceptors in Al x Ga 1-x As has been investigated by studying the nondegenerate localized vibrational modes of H-C As pairs with A1 symmetry, rather than those of isolated C As impurities. Infrared absorption and Raman scattering measurements have been made on Al x Ga 1-x As: 12 C epilayers that (a) had been exposed to a radio-frequency hydrogen (deuterium) plasma or (b) contained hydrogen incorporated during growth. Arguments are advanced that indicate that the H(D) atom should occupy a bond-centered site between C As and Ga atoms rather than between C As and Al atoms at low temperatures. An ab initio local-density-functional calculation indicates that the energy is then lowered by 0.24 eV. This analysis has led to the assignment of five antisymmetric stretch modes and five symmetric (X) modes to H-C As pairs at sites where the carbon atom that was originally unpaired had zero, one, two, three, or four Al nearest neighbors
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