Structural Characterization and Photoluminescent Properties ofZn_1-xMg_xO Films on Silicon

Zn_1-xMg_xO films have been grown on silicon at various substrate temperatures by pulsed laser deposition. The structural and photoluminescent properties of films as a function of substrate temperature were studied. The optimized substrate temperature is 650°C. The x-ray diffraction spectra indicate that the films are highly C-axis oriented, and no phase separation is observed. The crystal grain size of film is about 100 nm as examined by atomic force microscopy. The cross-sectional transmission electron microscopy verified C-axis orientation of the Zn_1-xMg_xO. These films showed ultraviolet photoluminescence at room temperature. The near-band-edge emission peak of the Zn_1-xMg_xO film deposited at 600°C has a blue shift (0.40 eV) larger than that of the film deposited at 500°C (0.33 eV). The ratio of the near-band-edge to defect level peak intensity is as large as 159.