Structural changes in a-Si:H film crystallinity with high H dilution

Journal Article · Sat Jan 15 04:00:00 EST 2000 · Physical Review. B, Condensed Matter and Materials Physics

DOI:https://doi.org/10.1103/PhysRevB.61.1677· OSTI ID:20215212

Mahan, A H ^[1]; Yang, J ^[2]; Guha, S ^[2]; Williamson, D L ^[3]

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1. National Renewable Energy Laboratory, Golden, Colorado 80401 (United States)
2. United Solar Systems Corp., Troy, Michigan 48084 (United States)
3. Colorado School of Mines, Golden, Colorado 80401 (United States)

Using infrared absorption (ir) spectroscopy, H evolution, and x-ray diffraction (XRD), the structure of high-H-dilution, plasma-enhanced chemical vapor deposition a-Si:H films ''on the edge of crystallinity'' is examined. From the ir Si-H wag mode peak frequency and the XRD results, we postulate the existence of very small Si crystallites contained within the as-grown amorphous matrix with the majority of the bonded H located on these crystallite surfaces. Upon annealing, a low-temperature H-evolution peak appears, and film crystallization is observed at temperatures as low as 500 degree sign C, which is far below that observed for a-Si:H films grown without H dilution. While the crystallite sizes and volume fraction are too small to be detected by XRD in the as-grown films, these crystallites catalyze the crystallization of the remainder of the amorphous matrix upon annealing, enabling the evolution of H at low temperatures. The large spatial inhomogeneity in the H bonding thus produced throughout the film is suggested to be one of the reasons for the reduced Staebler-Wronski effect observed in solar cells utilizing these films. (c) 2000 The American Physical Society.

• OSTI ID: 20215212
• Journal Information: Physical Review. B, Condensed Matter and Materials Physics, Journal Name: Physical Review. B, Condensed Matter and Materials Physics Journal Issue: 3 Vol. 61; ISSN 1098-0121
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
36 MATERIALS SCIENCE
CHEMICAL VAPOR DEPOSITION
CRYSTALLIZATION
EXPERIMENTAL DATA
HYDROGEN ADDITIONS
INFRARED SPECTRA
SILICON
SOLAR CELLS
STRUCTURAL CHEMICAL ANALYSIS
THIN FILMS
X-RAY DIFFRACTION