Density-of-state distribution and variable-range hopping transport in amorphous silicon prepared by ion bombardment

B. Ruttensperger, G. Müller, G. Krötz

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

Photothermal deflection spectroscopy measurements have been performed on amorphous silicon (a-Si) films produced by ion bombardment of crystalline silicon (c-Si). The analysis of the sub-bandgap optical absorption data provides, for the first time, detailed information about the localized density-of-states (LDOS) distribution in a system that exhibits variable-range hopping transport at the Fermi energy. We find that in a-Si the Fermi energy is pinned within a relatively nonuniform distribution of positive-correlation-energy states. Qualitatively, our findings support previous suggestions that the pre-exponential or σ0 problem in variable-range hopping might be related to LDOS non-uniformities around (EF). Comparing electronic transport data on a-Si produced by ion bombardment, to expectations based on the Mott theory, we show that the overall effect of LDOS non-uniformity and intra-site electron correlation is a significant reduction of the inter-site tunnelling distances. Possible reasons for this reduction are discussed.

Original languageEnglish
Pages (from-to)203-214
Number of pages12
JournalPhilosophical Magazine B: Physics of Condensed Matter; Statistical Mechanics, Electronic, Optical and Magnetic Properties
Volume68
Issue number2
DOIs
StatePublished - Aug 1993
Externally publishedYes

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