Photo-induced enhancement of the dark conductivity in nanocrystalline germanium/amorphous silicon composite thin films

J. K. Nangoi, K. Bodurtha, J. Kakalios

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

A light-induced increase in the dark conductivity is observed in composite thin films consisting of hydrogenated amorphous silicon (a-Si:H) containing nanocrystalline germanium (nc-Ge) inclusions, synthesized by co-deposition in a dual-chamber plasma enhanced chemical vapor deposition system. Unlike the Staebler-Wronski effect or persistent photoconductivity observed in amorphous semiconductors, this photo-induced excess conductivity is observed even in composite nc-Ge/a-Si:H films with a minimal photosensitivity. The decay of the excess conductivity follows a single-exponential time dependence, with a temperature independent time constant. We propose that spatial separation of photo-excited charge carriers by the compositional morphology present in the film, with tunneling of photo-excited holes into the germanium nanocrystalline inclusions, is involved in the creation and removal of this effect.

Original languageEnglish (US)
Article number165102
JournalJournal of Applied Physics
Volume124
Issue number16
DOIs
StatePublished - Oct 28 2018

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