Optical properties of thin films of Cu2ZnSnSe4 fabricated by sequential deposition and selenisation

Luckert, Franziska, Yakushev, Michael, Martin, Robert, Beattie, Neil, Zoppi, Guillaume, Moynihan, Matthew and Forbes, Ian (2010) Optical properties of thin films of Cu2ZnSnSe4 fabricated by sequential deposition and selenisation. In: 6th Photovoltaic Science Applications and Technology (PVSAT-6), 1-3 April 2010, University of Southampton, United Kingdom.

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Abstract

The search for new, low-cost semiconductor materials for large-scale production of solar cells has recently resulted in increased interest in the direct band gap quaternary semiconductor compound Cu2ZnSn(S,Se)4. A particular advantage compared to thin-film cells based on CuInGa(S,Se)2 (CIGS) is the absence of indium in the absorber layer. The constituent elements of Cu2ZnSn(S,Se)4 are all abundant in the earth’s crust, the material can be p-type doped and its absorption coefficient exceeds 104 cm–1 [1] in the visible range. An overview of progress on Cu2ZnSn(S,Se)4 thin film solar cell development has recently been published [2]. The conversion efficiency of Cu2ZnSnSe4 (CZTSe) based solar cells is around 4% [3] while that for Cu2ZnSnS4 (CZTS) based solar cells is close to 7% [4]. Recently, Todorov et al. [5] reported a record efficiency of 9.6% for a Cu2ZnSn(Se,S)4 based device. Photoluminescence (PL) is a very effective tool to study the electronic properties of semiconductors. PL spectra are highly sensitive to changes in the elemental composition of compound semiconductors which determines the type and concentrations of defects. Very few PL studies on CZTSe have been reported so far and the band gap in this material still has not been reliably established. Grossberg et al. [6] estimated a band gap value of 1.02 eV at 10 K which is in good agreement with the theoretical predictions of ~1.0 eV reported by Chen et al. [7]. However, an earlier report by Matsushita et al. [8] indicated a quite different value of 1.44 eV using optical absorption measurements at room temperature. In this paper we study the crystalline structure, the morphology, the elemental composition and the defect nature of CZTSe thin films using X-Ray diffraction (XRD), scanning electron microscopy (SEM), wavelength dispersive x-ray spectroscopy (WDX) and PL analysis, respectively.

Item Type: Conference or Workshop Item (Paper)
Subjects: H900 Others in Engineering
J500 Materials Technology not otherwise specified
Department: Faculties > Engineering and Environment > Physics and Electrical Engineering
Related URLs:
Depositing User: EPrint Services
Date Deposited: 16 Apr 2010 13:24
Last Modified: 13 Oct 2015 13:43
URI: http://nrl.northumbria.ac.uk/id/eprint/2426

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