Positron states in hydrogenated amorphous silicon

D. T. Britton, M. Härting, A. Hempel, G. Kögel, P. Sperr, W. Triftshäuser, M. Hempel, D. Knoesen

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

Low-hydrogen-concentration a-Si:H grown by HW-CVD forms a continuous random network with no detectable free volume in the form of microvoids, and no evidence of a microcrystalline phase. Over a wide temperature range we observe a single positron state in the amorphous network with a temperature-independent lifetime of 322 ps. From the temperature dependence of the positron diffusion we show that this is a localized state and present direct observation of hopping diffusion of positrons. On annealing up to 400 °C the amorphous network is seen to relax and the first stages of crystallization occur. There is also evidence of vacancy clustering to form a low concentration of microvoids. The structural relaxation has a very low-activation energy, around 0.1 eV, and is interpreted in terms of a reconfiguration of the fundamental defect identifed by positron annihilation.

Original languageEnglish
Pages (from-to)249-253
Number of pages5
JournalJournal of Non-Crystalline Solids
Volume299-302
Issue numberPART 1
DOIs
Publication statusPublished - Apr 2002

ASJC Scopus subject areas

  • Ceramics and Composites
  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Materials Chemistry

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