Structure and Photoluminescence of Polycrystalline Mg_xZn_1-xO Films

Different photoluminescence (PL) spectra are observed for rf magnetron sputtered polycrystalline Mg_0.25Zn_0.75O and Mg_0.37Zn_0.63O films on silicon substrates when excited by different wavelengths. When the excitation wavelength is 280nm, a UV emission peak at 370nm and a blue peak at 462nm are generated for the Mg_0.25Zn_0.75O film, and those two peaks for the Mg_0.37Zn_0.63O film shift to 366nm and 466nm, respectively. The wavelengths of the PL peaks are related to the excitation wavelength. The stronger peak is obtained in the blue band due to a large number of oxygen vacancies caused by excess Zn and Mg atoms, while the weaker peak is obtained in the ultraviolet band.