Title:
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Application of Pulsed D.C. Magnetron sputtering deposition for the component layers of CuInSe2 thin film photovoltaic cells
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The Pulsed D.C. Magnetron Sputtering (PDMS) process has been investigated for the deposition of the component layers that are used in the production of copper indium diselenide, CuInSe 2 (CIS), thin film solar cells. PDMS can use high plasma densities with long term arc free operation for the reactive sputtering of dielectric materials and can produce films with good crystalline properties, even at low substrate temperatures. However, the technique has not previously been applied to photovoltaic cell fabrication. Customised powder target PDMS systems have been designed and constructed for this work. Various operating parameters which affect the film characteristics have been studied to allow optimisation of the sputtering process. This low temperature deposition technique allows the use of flexible, low melting point substrates and can also reduce the temperature induced damage to the layers associated with conventional D.C. and R.F. sputtering processes. A typical CIS based cell consists of a molybdenum back contact layer, a CIS absorber layer, a cadmium sulphide buffer layer and a zinc oxide top layer. In this study, toxic cadmium sulphide was replaced by indium sulphide and the top layer employed indium oxide which could be changed from intrinsic to highly conducting by adjustment of the oxygen flow during sputtering. The deposited layers were characterised using various analytical tools such as x-ray diffraction, atomic force microscopy, scanning electron microscopy, UV-Vis-NIR spectrophotometry, four point probe etc. Material characterisation results indicated the suitability of using PDMS to deposit the component layers required in CIS solar cell fabrication.
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