Effect of annealing ambient on electrical and optical properties of Ga-doped MgxZn1−xO films

2 at.% Ga-doped MgxZn1−xO (x = 0–8%) films have been prepared by sol–gel dip-coating method, and the effects of three different post annealing ambient: (a) vacuum annealing under air pressure of ∼10−2 Pa; (b) annealing in nitrogen atmosphere, and (c) annealing in argon-hydrogen (96%argon + 4%hydrogen) atmosphere on the electrical and optical properties of the films are investigated. When treated by these three different post-annealing ambient, both the resisitivity and band gap of the films increase with Mg doping contents increasing from 0 to 8 at.%. The vacuum annealed films show much lower resistivity than those treated in nitrogen or argon–hydrogen atmosphere, and the transmittance of the vacuum annealed films (∼70%) is also lower than those annealed by the other two methods (∼90%) in visible region. It shows that different post annealing ambient and ion doping could modify the optoelectronic properties of ZnO films.