Properties of Al heavy-doped ZnO thin films by RF magnetron sputtering

Al-doped ZnO films were deposited by RF magnetron sputtering. From the X-ray diffraction and scanning electron spectrometer studies, wurtzite structure with (0 0 2) orientation ZnO thin films were obtained at Al concentration below 15 atomic percent (at.%). As the Al concentration above 15 at.%, the thin films did not fully crystallize. Two new emission peaks occurred at 351 nm and 313 nm when the Al doping above 15 at.% from the photoluminescence spectrum, and the peaks shift towards the shorter wavelengths with increasing the Al concentration. X-ray photonic spectra of O 1s conformed the amount of oxygen captured by Al3+ increasing as the Al3+ concentration increasing due to the dominant Al3+ possess high charge in competition with Zn2+ in the matrix of ZnO.