Vibrational lifetimes of light impurities in silicon

S. K. Estreicher, D. West

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Light impurities in covalent materials, such as H or O in Si, are characterized by high-frequency local vibrational modes (LVMs) far above the phonon frequencies of the host crystal. Upon excitation, such LVMs are expected to have long lifetimes since their decay involve multi-phonon processes. Yet, time-resolved infrared absorption spectroscopy reveals that the vibrational lifetimes of almost identical LVMs sometimes differ by up to two orders of magnitude. Indeed, the low-temperature lifetimes of the 2062 cm-1 mode of the H2* complex, the 1998 cm-1 mode of bond-centered hydrogen HBC+ and the 2072 cm-1 mode of the di-vacancy di-hydrogen complex VH · HV are 4, 8 and 295 ps, respectively. More surprising still, the measured lifetime of the asymmetric stretch of interstitial O in Si changes by almost an order of magnitude with the isotope of O or one of its Si neighbors. In this paper, ab-initio molecular dynamic simulations in periodic supercells are used to calculate vibrational lifetimes. The calculations predict the correct lifetimes of the various defects in the range 50 < T < 200 K and provide critical insight into the decay processes.

Original languageEnglish
Pages (from-to)196-199
Number of pages4
JournalNuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms
Issue number1-2
StatePublished - Dec 2006


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