Transparent conductive oxides (TCO) having a wide bandgap, high transparency, and conductivity are necessary materials for fabricated photovoltaic heterostructure solar cells, transparent conducting electrodes, window materials, displays, etc. Today, the most widely used TCO are indium tin oxide (ITO), which has suitable characteristics. However, ITO has some negative factors such as the limited deposits of indium in the Earth's crust causing a constant increase in its cost, and also high toxicity and environmental hazard industrial-scale production. These factors are the reasons for replacing ITO with more safe, economically profitable, and affordable materials. Zinc oxide doped by donor impurities of Al, Ga, or In is a promising material for future technologies of electronics and optoelectronics. In economic terms, aluminum is the most favorable donor impurity. [1] Al-doped ZnO (ZnO:Al) overcomes all aforementioned negative factors. The material is nontoxic, the prevalence of raw materials in the Earth's crust, high stability to hydrogen plasma, and temperature changes. ZnO has a wide direct band gap (%3.34 eV at room temperature) that allows to be highly transparent (%85-95%) in a wide range of wavelengths (300-1000 nm). In several of our previous articles, we have comprehensively investigated the effect of deposition technological parameters on the structural, optical, and electrical properties of zinc oxide films. [2][3][4][5] However, the problem of small electroactivity (EA) for introduced donor impurities into the ZnO lattice still exists. [6] EA of the impurity is a very important characteristic of a doped semiconductor. The conductivity of semiconductor doping by donor impurity (in our case Al in ZnO) is determined not only by the mobility of free carriers but also their concentration, and, hence, the EA of donor impurity. The EA means the number of conductivity electrons that which donor impurity atom delivers to the conduction band (EA ¼ 100% means that each Al ion, substituted Zn ion in cation sublattice deliver one electron into the conduction band). [7] Really EA < 100%, because of different reasons. When ZnO is doped with aluminum, the intrinsic