Radical-source molecular beam epitaxy of ZnMgO and ZnCdO alloys on ZnO substrates

Abstract

We report on a dramatic improvement of the crystalline quality of ZnMgO and ZnCdO epilayers using Bridgman-grown ZnO substrates. ZnMgO alloys grow pseudomorphically over several 100nm and the (0002) ω-rocking curve width is as low as 19arcsec. Strain inhomogeneities in low-temperature grown ZnCdO are significantly reduced and the rocking width is lowered down to 45arcsec. Despite the high crystalline perfection, the optical properties of the films are mainly determined by their ternary character.