Influence of deposition temperature on amorphous structure of PECVD deposited a-Si:H thin films

Journal article (2011)

Authors

J Mullerova External organisation
M. Fischer Photovoltaic Materials and Devices - EEMCS
M Netrvalova External organisation
M. Zeman Photovoltaic Materials and Devices - EEMCS
P Sutta External organisation
Research Group
Photovoltaic Materials and Devices (EEMCS) (TU Delft)
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Published Date

2011

Language

English

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Faculty

Electrical Engineering, Mathematics and Computer Science

Department

Electrical Sustainable Energy

Research Group

Photovoltaic Materials and Devices

Abstract

The effect of deposition temperature on the structural and optical properties of amorphous hydrogenated
silicon (a-Si:H) thin films deposited by plasma-enhanced chemical vapour deposition (PECVD) from silane
diluted with hydrogen was under study. The series of thin films deposited at the deposition temperatures
of 50 ¿ 200°C were inspected by XRD, Raman spectroscopy and UV Vis spectrophotometry. All samples
were found to be amorphous with no presence of the crystalline phase. Ordered silicon hydride regions
were proved by XRD. Raman measurement analysis substantiated the results received from XRD showing
that with increasing deposition temperature silicon-silicon bond-angle fluctuation decreases. The optical
characterization based on transmittance spectra in the visible region presented that the refractive index
exhibits upward trend with increasing deposition temperature, which can be caused by the densification
of the amorphous network. We found out that the scale factor of the Tauc plot increases with the deposition
temperature. This behaviour can be attributed to the increasing ordering of silicon hydride regions.
The Tauc band gap energy, the iso-absorption value their difference were not particularly influenced by
the deposition temperature. Improvements of the microstructure of the Si amorphous network have been
deduced from the analysis.