Effects Of Al, Ga-Doping On Transparent Conducting Properties Of Amorphous Zno-Sno2 Films

ZnO-SnO2 thin films were deposited on glass substrates (Corning#1737) by DC magnetron sputtering. In this works, we examined a doping effect on a ZnO target on transparent conducting properties. ZnO:Al(4wt%), and ZnO:Ga(6wt%) targets were used for a dopant-free ZnO target. Substrate temperature was held at 250 degrees C. The current ratio 6 was defined as I-Zn/I-Zn+I-Sn (ZnO target current divided by the sum of ZnO and SnO2 target currents). Compositions of as-deposited films were changed with the current ratio delta. In the ZnO-SnO2 system, amorphous transparent films appeared over the range of 0.338 <=delta <= 0.73. On the other hand, in the ZnO:Al(4wt%)-SnO2 and ZnO:Ga(6wt%)-SnO2 systems, they appeared over the range of 0.20 <=delta <= 0.90 and 0.33 <=delta <= 0.80, <=delta <= respectively. The minimum resistivity of amorphous films was about 3.0x10(-2) Omega cm for all the systems. Al, Ga doping effect on film resistivity was not clear very much. But optical transparencies were 80-90% in visible region, 10% higher than those of ZnO-SnO2 system at average. Optical band gap for the films with the same current ratio 8 also was enhanced by the Al, Ga doping.