Effects of high-dose Ge ion implantation and post-implantation annealing on ZnO thin films

This paper reports that ion implantation to a dose of 1×10¹⁷ions/cm² was performed on c-axis-orientated ZnO thin films deposited on(0001) sapphire substrates by the sol-gel technique. After ion implantation,the as-implanted ZnO films were annealed in argon ambient at differenttemperatures from 600-900℃. The effects of ion implantationand post-implantation annealing on the structural and optical properties ofthe ZnO films were investigated by x-ray diffraction (XRD),photoluminescence (PL). It was found that the intensities of (002) peak andnear band edge (NBE) exitonic ultraviolet emission increased with increasingannealing temperature from 600-900℃. The defect related deeplevel emission (DLE) firstly increased with increasing annealing temperaturefrom 600- 750℃, and then decreased quickly with increasingannealing temperature. The recovery of the intensities of NBE and DLE occursat sim 850℃ and sim 750℃ respectively. The relativePL intensity ratio of NBE to DLE showed that the quality of ZnO filmsincreased continuously with increasing annealing temperature from 600 - 900℃.