“…Many groups have reported the influence on ZnO thin films of metal dopants, including In [10], Al [11][12][13][14], Fe [12,15], Mn [16], Mg [17], and Ga [12,18], to replace indium-doped tin oxide or fluorine-doped tin oxide [1,3]. One promising dopant is Cu, which has been reported to show enhanced properties such as higher conductivity [19], diluted magnetic properties [15], and improved crystal quality [20].…”