Co-sputtered Cd/sub 2/SnO/sub 4/ films as front contacts for CdTe solar cells

Abstract

Cd/sub 2/SnO/sub 4/ thin films were investigated from a materials point of view as well as from an application point of view through their incorporation into CdTe based solar cells. Cd/sub 2/SnO/sub 4/ was deposited by co-sputtering from CdO and SnO/sub 2/ targets. The lowest resistivity achieved was 2.01/spl times/10/sup -4/ /spl Omega/-cm with a mobility of 29.2 cm/sup 2//V/s and a carrier concentration of 8.47 /spl times/ 10/sup 20/ cm/sup -3/. For this same sample the average transmission was over 90% over the visible and near IR spectrum (400-900nm). When Cd/sub 2/SnO/sub 4/ were used as part of the front contact in thin film CdTe solar cells V/sub oc/'s over 840 mV, J/sub sc/'s over 23 mA/cm/sup 2/, and ff's over 68.0% were obtained with the best to-date efficiency being 14.0%.