Annealing effect on PL properties of ALE-ZnO

초록

High quality ZnO thin films were deposited on the sapphire (0001) substrate using an ALE technique. DEZn and H2O were used as a zinc source and an oxidant, respectively. Nitrogen was used as a purge gas. Two kinds of substrate temperature were used one of which is 170℃ in the temperature range of atomic layer deposition and the other of which is 400℃ in the temperature range of chemical vapor deposition. The ZnO thin films were subsequently annealed at 600, 800, and 1000℃ for 1 hr in oxygen atmosphere. The photoluminescent spectrometry was used to evaluate the luminescent characteristics of the films. The PL characteristics were significantly enhanced by annealing. A strong peak was obtained in the green band for the ZnO thin film deposited at 400℃ due to the large amount of oxygen vacancies caused by excess Zn atoms. While nearly no peak appeared for the one deposited at 170℃. Both the PL intensity peaks in the UV light and visible light regions are increased by annealing the ZnO film in an oxygen atmosphere. In contrast, only the PL intensity peak in the UV light region is selectively increased by annealing it in a nitrogen atmosphere.