Cg. Van De Walle et Jp. Goss, Energetics and vibrational frequencies of interstitial H-2 molecules in semiconductors, MAT SCI E B, 58(1-2), 1999, pp. 17-23
We report a comprehensive investigation of the incorporation of H-2 molecul
es in semiconductors. We consider five different materials (Si, GaAs, InAs,
GaP and GaN), and use a density-functional-pseudopotential approach. Combi
ned with calculations for H-2 in vacuum, these results enable us to examine
trends and develop an understanding of the physics of incorporation of a s
trongly bound molecule in a semiconducting environment. We find that the vi
brational frequency of the interstitial molecules is shifted down significa
ntly compared to the free molecule. We also investigate anharmonicity in th
e molecular vibrations. The results confirm a recent assignment of Raman li
nes to interstitial H-2 in GaAs, but contradict an assignment claiming that
the frequency for H-2 in Si is close to the free-molecule value. Finally,
we calculate and discuss diffusion of H-2 molecules through a Si crystal. (
C) 1999 Elsevier Science S.A. All rights reserved.