Growth of high quality Zn0.9Mg0.1O films on c-plane sapphire substrates by plasma-assisted molecular beam epitaxy

We report the growth and characterization of single-crystalline, epitaxial Zn0.9Mg0.1O films on c-plane sapphire substrates with MgO buffer layer by plasma-assisted molecular beam epitaxy. The quality of the Zn0.9Mg0.1O epilayers is evidenced by a Hall mobility of more than 60 cm(2) V-1 s(-1) at room temperature and an X-ray diffraction (XRD) rocking curve full-width at half-maximum of 47 arcsec for the (0002) reflection. A screw dislocation density of 4 x 10(6) cm(-2) is estimated by XRD. Transmission electron microscopy revealed that the thickness of the MgO buffer layer is about 3.5 nm, and a highly c-axis oriented Zn0.9Mg0.1O (0002) reflection corresponding to the wurtzite-phase is observed. Alloying with Mg is found to widen the bandgap energy of the ZnO, and luminescence is observed at 3.502 eV at low temperature. (C) 2013 Elsevier B.V. All rights reserved.