Crystal orientations of β‐Ga₂O₃ thin films formed on m‐plane and r‐plane sapphire substrates

Abstract

We have used X‐ray pole figure analyses to study crystal orientations of β‐Ga2O3 thin films formed on (100) m‐plane or (102) r‐plane sapphire substrates prepared by gallium evaporation in oxygen plasma. The (−201) plane of β‐Ga2O3 on the (100) m‐plane was inclined to be along two (110) a‐planes. Crystals of (−201)‐oriented β‐Ga2O3 exhibit six‐fold symmetry in which a β‐Ga2O3 crystal is rotated every 60° from [001] for each a‐plane. In all, twelve kinds of β‐Ga2O3 crystals formed on m‐plane sapphire substrate. Similarly, the (−201) plane of β‐Ga2O3 on the (102) r‐plane was inclined to be along to two (113) n‐plane. Crystals of (−201)‐oriented β‐Ga2O3 exhibit three‐fold symmetry with a β‐Ga2O3 crystal rotated every 120° from the opposite direction of projection of the c‐axis of each n‐plane. In all, six kinds of β‐Ga2O3 crystals formed on the r‐plane sapphire substrate. These observations can be explained by comparing oxygen atomic arrangements on the β‐Ga2O3 (−201) plane with those on the sapphire (110) a‐plane and (113) n‐plane.

Density Functional Theory Simulations of Water Adsorption and Activation on the (−201) β‐Ga2O3 Surface

“…For example, various experiments indicate that (−201) is the preferred growth direction for thin films grown on c‐plane sapphire . This orientation can be related to the fact that the oxygen atoms of the (001) plane of the sapphire substrate have a similar atomic arrangement compared to the (−201) plane of β‐Ga 2 O 3 ,. Interestingly, the XRD pattern of catalytically grown Zn‐doped p‐type β‐Ga 2 O 3 nanowires shows a significant peak at (−201) .…”

Epitaxial Growth and Solar‐Blind Photoelectric Characteristic of Ga2O3 Film on Various Oriented Sapphire Substrates by Plasma‐Enhanced Chemical Vapor Deposition

“…The reason is the atoms in the orientation of β‐Ga 2 O 3 are unmatched with atom arrangement of m ‐ and r ‐ sapphire substrates. [ 22,23 ]…”

Crystal orientations of β‐Ga2O3 thin films formed on n‐plane sapphire substrates

“…We have previously studied the crystal orientation of β‐Ga 2 O 3 crystals formed on the (100) m ‐plane and (102) r ‐plane of sapphire substrates . The results of a number of studies on the crystal orientation of β‐Ga 2 O 3 prepared on several types of sapphire substrates with different crystal planes are summarized in Table .…”

“…In the present study, we measured, for the first time, the crystal orientations of β‐Ga 2 O 3 formed on (113) n ‐plane sapphire substrates and analyzed these orientations on the basis of crystal models. The reason why we selected n ‐plane sapphire substrate is because (−201) β‐Ga 2 O 3 was parallel to the (113) plane of the sapphire substrate when a (102) r ‐plane sapphire substrate was used .…”