Dependence of structural, electrical, and optical properties of ZnO : Al films on substrate temperature

ZnO:Al (ZAO) films were deposited on fused silica substrates heated to 350 degreesC by de magnetron reactive sputtering from a Zn target mixed with 1. 5 wt% Al. Films deposited on a substrate heated to a temperature between ro om temperature and 300 degreesC were (001)-oriented crystals, but those gro wn at 350 degreesC consisted of crystallites with (001) and (101) orientati ons. The dependence of electrical properties such as resistivity, carrier c oncentration, and Hall mobility on temperature was measured. The results in dicate that the carrier concentration and Hall mobility increase with incre asing temperature up to 250 degreesC, though the Al content remains unchang ed in this temperature range. The probable mechanisms are discussed. The mi nimum resistivity of ZAO films is 4.23 x 10(-4) R cm, with a carrier concen tration of 9.21 x 10(20) cm(-3) and a Hall mobility of 16.0 cm(2) v(-1) s(- 1). The films show a visible transmittance of above 80%.