Hydrogenated amorphous silicon p¿i¿n solar cells deposited under well controlled ion bombardment using pulse-shaped substrate biasing

Journal article (2012)

Authors

M.A. Wank Photovoltaic Materials and Devices - EEMCS
R.A.C.M.M. van Swaaij Photovoltaic Materials and Devices - EEMCS
MCM van de Sanden External organisation
M. Zeman Photovoltaic Materials and Devices - EEMCS
Research Group
Photovoltaic Materials and Devices (EEMCS) (TU Delft)
More Info
expand_more

Published Date

2012-5

Language

English

Reuse Rights

Other than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons.

Faculty

Electrical Engineering, Mathematics and Computer Science

Department

Electrical Sustainable Energy

Research Group

Photovoltaic Materials and Devices

Abstract

We applied pulse-shaped biasing (PSB) to the expanding thermal plasma deposition of intrinsic hydrogenated amorphous silicon layers at substrate temperatures of 200¿°C and growth rates of about 1¿nm/s. Fourier transform infrared spectroscopy of intrinsic films showed a densification with increasing deposited energy and a reduction in void content, whereas dual-beam photoconductivity measurements showed an increase in Urbach energy above 4.8¿eV/Si atom. From dark conductivity and photoconductivity measurements, we determined a maximum photoresponse of 2¿×¿106 at 3¿eV/Si atom, which decreased at higher deposited energies because of a higher dark conductivity as a result of a lower band gap. p¿i¿n solar cells with PSB applied during the intrinsic layer deposition showed initial energy conversion efficiencies of 7.4% at around 1¿eV/Si atom. Decreasing open-circuit voltage at >1¿eV/Si atom can be related to a lower band gap, whereas the short-circuit current drops at >4.8¿eV/Si atom, predominantly because of hole collection losses as determined from quantum efficiency measurements. The reduced fill factor for >1¿eV/Si atom was presumably related to a decrease in mobility-lifetime product because of an increase in defect density.