“…[2,4,5] Among these methods, doping heteroatoms into the pure ZnO materials is frequently applied to obtain the desired characteristics in particular applications. For example, to obtain n-type ZnO materials applying in gas sensing, solar cells or panel displays, group-IIIA elements (B, Al, Ga, In) [6][7][8] was introduced into ZnO materials; to get p-type ZnO materials, group-IA elements (Li, K, Na) [9][10] were doped into ZnO materials which are appropriate for photoelectronic devices; to enhance applications in detecting volatile organic compounds, Au was doped in ZnO. This is due to Au doped ZnO reduce the band gap structure which enhances gases interactions.…”