Properties of shallow donors in ZnMgO epilayers grown by metal organic chemical vapor deposition

Abstract

Influence of thermally diffused aluminum atoms from sapphire substrate on the properties of ZnO epilayers grown by metal-organic chemical vapor deposition J. Vac. Sci. Technol. A 29, 03A106 (2011) The grown samples were investigated by x-ray photoelectron spectroscopy and photoluminescence. The magnesium (Mg) concentration was varied between 0% and 3% in order to study the properties of shallow donors. The free and donor bound excitons could be observed simultaneously in our high quality Zn 1Àx Mg x O epilayers in the photoluminescence spectra. The results indicate that both built-in strain and Mg-concentration influence the donor exciton binding energy. It clearly shows that the donor exciton binding energy decreases with increasing Mg-concentration and with increasing built-in strain. Furthermore, the results indicate that the donor bound exciton transition energy increases with decreasing strength of the built-in strain if the Mg-concentration is kept the same in the Zn 1Àx Mg x O epilayers. V C 2014 AIP Publishing LLC.