Sn-doped indium oxide (ITO) films deposited at temperatures <250°C by r.f. magnetron sputtering are investigated for use as transparent back-contact electrodes to CdS/CdTe top cells in two-junction, mechanically stacked tandem-cell designs. Results show that carrier mobility increases with substrate temperature while beneficial changes in carrier activation occurs at a substrate temperature ~230°C. Small additions of oxygen to the sputtering environment are effective at reducing near infrared (NIR) absorption. Control of these deposition parameters has produced ITO films with NIR absorption (860–1300 nm) < 10%, and electrical resistivity of <1x10-3 ohm-cm.