A high-resolution electron microscopy study of Mg_xZn_1–xO films grown on MgO/c-sapphire

We report on the microstructure of Mg_xZn_1–xO films grown on MgO/c-sapphire by P-MBE. Cross sectional specimens of three layers with rock salt, wurtzite, and mixed crystal structure were studied by high-resolution transmission electron microscopy (HRTEM). Selected area diffraction pattern (SADP) and fast fourier transform (FFT) were also employed to analyze the samples. The results indicate the growth of cubic-MgZnO along the [111] direction accompanied by twinning. HRTEM micrograph of wurtzite-MgZnO confirmed that initial stage of the growth starts with a cubic structure and then changes to the wurtzite phase. Our results demonstrate that by introducing a thin MgO buffer layer, growth of cubic-MgZnO with low Mg content is feasible. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)