Electrical properties of electrodeposited CdTe photovoltaic devices on metallic substrates: study using small area Au–CdTe contacts L.A. Kosyachenko a, * , X. Mathew b,1 , V.V. Motushchuk a , V.M. Sklyarchuk a a Chernivtsi National University, 58012 Chernivtsi, Ukraine b Centro de Investigacion en Energia-UNAM, 62580, Temixco, Morelos, Mexico Received 1 November 2004; received in revised form 16 January 2005; accepted 19 January 2005 Available online 14 March 2005 Communicated by: Associate Editor T.M. Razykov Abstract Charge transport properties of the Schottky diodes fabricated on n-CdTe layers electrodeposited on stainless steel foil are investigated. The small area Au–CdTe contacts facilitated the investigation of the role of shunt and series resis- tances on the I–V characteristics of the thin-film CdTe device. The charge transport mechanism in these diodes is found to be generation–recombination in the depletion layer and over-barrier electron flow at low and higher bias voltages, respectively. By using this model a quantitative theoretical analysis of the current–voltage characteristics of the diodes is possible. Ó 2005 Elsevier Ltd. All rights reserved. Keywords: Solar cells; CdTe; Electrodeposition; Charge transport 1. Introduction Investigations of the past decades proved doubtlessly the prospect of thin-film CdTe solar cells. The direct bandgap and high optical absorption coefficient make the CdTe one of the promising absorber layers among the thin-film photovoltaic materials. The theoretical limit of the solar to electrical energy conversion effi- ciency of a CdTe based device is 28–30% (Sze, 1981). The highest reported efficiency of a CdTe/CdS solar cell is 16.5% (NREL, 2001) much lower than the theoretical limit, and the reason for this lower performance is not conclusively established. Developing solar cells on thin metal foils is interesting, since it can provide mechanical durability higher than that of the conventional glass- based devices. Further, the solar cells on thin foil sub- strates are flexible, light in weight and can open up new technological possibilities. The knowledge of the electrical properties of the bar- rier where a photo-voltage is generated is important in the development and optimization of any photovoltaic device. In the past, interesting investigations of the metal/CdTe contacts were performed using single crystal 0038-092X/$ - see front matter Ó 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.solener.2005.01.009 * Corresponding author. Tel.: +38 0372 522949/2221; fax: +38 0372 584078/551809. E-mail addresses: lakos@chv.ukrpack.net (L.A. Kosyachen- ko), xm@cie.unam.mx (X. Mathew). 1 Tel.: +52 777 3250052, fax: +52 777 3250018. Solar Energy 80 (2006) 148–155 www.elsevier.com/locate/solener