Blue shift in photoluminescence of ZnO thin films depending on post-annealing temperature

초록

ZnO thin films on (001) sapphire substrates have been deposited by pulsed laser deposition (PLD) technique using an Nd:YAG laser with a wavelength of 266㎚. Before post-annealing treatment in the oxygen ambient, the experiment of the deposition of ZnO thin films has been performed for substrate temperatures in the range of 300~450 ℃ and flow rate of 100~700 sccm. In order to investigate the effect of post-annealing treatment of ZnO thin films deposited at fixed oxygen pressure of 350 sccm and at the substrate temperature of 400 ℃, the films have been annealed at various temperatures after deposition. As the post-annealing temperature increases, the nanocrystallite size was increased which resulted in the shift of room temperature visible photoluminescence of ZnO thin films from 475 ㎚to the shorter wavelength of 435㎚. After post-annealing treatment in the oxygen ambient, the structural properties of ZnO thin films were characterized by X-ray diffraction (XRD), SEM and the optical properties of the ZnO were characterized by photoluminescence (PL)