Electronic transitions in mixed phase crystalline/amorphous silicon in the low crystalline fraction regime
Amorphous silicon films were prepared by dc reactive magnetron sputtering under conditions approaching the phase transition to microcrystallinity. using TEM imaging these films were found to contain clusters of 5 to 50 nm sized Si crystallites embedded in an amorphous silicon matrix. Photocapacitance and transient photocurrent sub-band-gap optical spectra of this material appear to consist of a superposition of a spectrum typical of amorphous silicon together with an optical transition, with a threshold near 1.1 eV, that exhibits a very large optical cross section. This transition arises from valence band electrons being optically inserted into empty levels lying within the amorphous silicon mobility gap. Using modulated photocurrent methods they have determined that these states also dominate the electron deep trapping in this material. They argue that these states arise from defects at the crystalline-amorphous boundary.
- Research Organization:
- Univ. of Oregon, Eugene, OR (US)
- Sponsoring Organization:
- National Science Foundation (NSF); US Department of the Navy, Office of Naval Research (ONR); USDOE
- DOE Contract Number:
- FG02-91ER45439
- OSTI ID:
- 20107943
- Resource Relation:
- Conference: 1999 Materials Research Society Spring Meeting, San Francisco, CA (US), 04/05/1999--04/09/1999; Other Information: PBD: 1999; Related Information: In: Amorphous and heterogeneous silicon thin films: Fundamentals to devices -- 1999. Materials Research Society symposium proceedings: Volume 557, by Branz, H.M.; Collins, R.W.; Okamoto, Hiroaki; Guha, S.; Schropp, R. [eds.], 908 pages.
- Country of Publication:
- United States
- Language:
- English
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