Polycrystalline CuIn/sub 1-x/Ga/sub x/Se/sub 2/ thin film PV solar cells prepared by two-stage selenization process using Se vapor

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Abstract
Novel two-stage Se vapor selenization of magnetron sputtered metallic precursors and Ga incorporation using single Cu-Ga(22 at.%) alloy target have been developed for preparation of well-adherent, large, compact, well-faceted polyhedral grain CuIn/sub 1-x/Ga/sub x/Se/sub 2/ thin films having optimum composition Cu:In:Ga:Se of 22.95:25.03:1.40:50.63. Cu-In-Ga precursor homogenization by in situ heat-treatment at /spl sim/90/spl deg/C for 10 minutes prior to first selenization, selenization temperature of 550-560/spl deg/C, and Se vapor incidence rate of 50 /spl Aring/ sec/sup -1/ resulted in improved morphology of completed CuIn/sub 1-x/Ga/sub 2/Se/sub 2/ thin films, and solar cells with open circuit voltage V/sub oc/ 377 mV, short circuit current density J/sub sc/ of 34.8 mA, fill factor (FF) of 62.5%, active area efficiency of 8.2% (total area efficiency 5.8% limited by FF 49.1%) and fairly constant spectral response over the spectral range.