Photoluminescence of ZnO quantum dot films prepared by low temperature chemical vapor deposition



Films have been prepared at substrate temperatures of 125 to 200 °C by chemical vapor deposition. As a substrate temperature decreases, the grain sizes of the films are decreased. From transmission electron microscopic observation, the film grown at 125 °C is found to be constructed from ZnO quantum dots with 5 nm in diameter. Photoluminescence spectra in ultraviolet region at 40 K or less are assigned to both free electron-acceptor and donor-acceptor pair emissions, whereas photoluminescence spectra at temperatures higher than 50 K are due to the free electron-acceptor emission. The peak energy of the free electron-acceptor emission for the film deposited at 125 °C is 0.143 eV larger than that for the film deposited at 200 °C. The blue shift of the emission peak is ascribed to the quantum confinement effect. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)