CRYSTALLOGRAPHIC ORIENTATION AND MORPHOLOGY OF EPITAXIAL IN2O3 FILMS GROWN ON MGO(001) SINGLE-CRYSTAL SUBSTRATES

Thin epitaxial In2O3 films were grown on MgO(001) single crystal subst rates by electron beam evaporation in a high-vacuum chamber. During th e evaporation, the substrate was heated to temperatures between 600 an d 850 degrees C, and different oxygen background pressures were applie d. The films were first characterized by X-ray diffraction (XRD), scan ning electron microscopy (SEM) and energy dispersive X-ray (EDX). Stru cture, morphology and crystallographic orientation of the film and the MgO/In2O3 interfaces were then investigated by transmission electron microscopy/selected area electron diffraction (TEM/SAED), In all sampl es the major part of the film area grows with the In2O3(111) plane par allel to the MgO(001) surface, and shows an in-plane orientation with four domains occurring, characterized by the In2O3(<1(1)over bar 10>) plans being parallel to one of the four different MgO(110) planes. The se parts of the In2O3 films consist of grains with a columnar structur e, with a typical grain diameter of 50 to 200 nm for a film thickness ranging from 120 to 150 nm. and an extreme small rocking curve FWHM up to 0.1 degrees. A minor part of the film area was found in a ''cube-t o-cube'' orientation: In2O3(001)parallel to MgO(001); In2O3[100]parall el to MgO[100]. The amount of thr minor part film area decreases with increasing substrate temperature down to lower than 0.3%. (C) 1997 Els evier Science S.A.