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Bonding of H-CAs pairs in Al(x)Ga(1-x)As alloys

Bindung von H-CAs Paaren in Al(x)Ga(1-x)As Legierungen


Physical Review. B 50 (1994), Nr.15, S.10628-10636
ISSN: 0163-1829
ISSN: 1098-0121
ISSN: 0556-2805
Fraunhofer IAF ()
AlxGa1-xAs; H-CAs Paar; H-CAs pair; local vibrational mode spectroscopy; Spektroskopie lokaler Schwingungsmoden

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