Electrical and optical properties of ZnO films prepared by sputtering of ZnO targets containing AlN

摘要

ZnO films prepared from the ZnO target containing 2% AlN are transparent irrespective of radio frequency (RF) power. The obtained ZnO films have the carrier density of 3.8 × 10~(20) cm~(-3) or less and the low mobility of 5.3-7.8 cm~2/(V s). In the case of 5% AlN target, ZnO films prepared at 40,60 and 80 W are transparent, whereas ZnO films prepared at 100 and 120 W are colored. As RF power increases from 40 to 120 W, the carrier density increases straightforwardly up to 5.5 × 10~(20) cm~(-3) at 100 Wand is oppositely reduced to 3.2 × 10~(20) cm~(-3) at 120 W. In the case of 10% AlN target, ZnO films prepared at 60 Wor more are colored, and have the carrier density of 4 × 10~(20) cm~(-3) or less. The N-concentration in these colored films is estimated to be 1 % or less. The Al-concentration in the ZnO films prepared from the 5 and 10% A1N targets is higher than 2%. The carrier density of the ZnO films containing Al and N atoms is nearly equal to that of ZnO films doped with Al atoms alone. There is no evidence in supporting the enhancement of the carrier density via the formation of N-Al_xZn_(4-x) clusters (4 ≥ x ≥ 2).