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Measuring CdS/CdTe solar cells back contact barrier height Mohammed K. Al Turkestani1 and Ken Durose2 1 Department of Physics, Umm Al-Qura University, Saudi Arabia 2 Stephenson Institute for Renewable Energy/Department of Physics, University of Liverpool, UK The back side or dark contact to CdTe solar cells presents a fundamental limit to PV performance since metallic contacts to p-CdTe inevitably have a non-Ohmic contact. In this work a) methods to measure the back contact Schottky barrier height in thin film solar cells are evaluated and b) the methods are used to evaluate the barrier heights of a number of contacting procedures and materials are measured. Two methods for measuring the back contact barrier height were compared. i) The first relies on determining the voltage value at which the roll over effect (forward bias current limitation) starts occurring in the J-V characteristics. However, the procedure for identifying this voltage can lead to uncertainties, especially with weak roll over. ii) The second method assumes that the solar cell series resistance, Rs, is predominantly due to the back contact. Thus the back contact barrier height can be calculated from the dependence of Rs on temperature, T. Simplifications, improvements and limitations of these methods are presented. Both methods yielded results with a high level of agreement. Barrier heights for a range of different contacts for CdTe solar cells were then measured. Three contact materials were investigated, these being Au, Sb2Te3 and As2Te3. Different etching procedures were also used as part of the contacting protocols, these being either nitric-phosphoric acid (wet etching) or plasma (dry etching) or the control (no etching). Both the values of the barrier height (generally in the range 0.2 – 0.45 eV) and the effect of the back surface treatment on those values are presented and discussed. Presentation: Poster