α-Ga2O3 is a metastable phase of Ga2O3 of interest for wide bandgap engineering since it is isostructural with α-In2O3 and α-Al2O3. α-Ga2O3 is generally synthesised under high pressure (several GPa) or relatively high temperature (∼500 °C). In this study, we report the growth of α-Ga2O3 by low temperature atomic layer deposition (ALD) on sapphire substrate. The film was grown at a rate of 0.48 Å/cycle, and predominantly consists of α-Ga2O3 in the form of -oriented columns originating from the interface with the substrate. Some inclusions were also present, typically at the tips of the α phase columns and most likely comprising ε-Ga2O3. The remainder of the Ga2O3 film – i.e. nearer the surface and between the α-Ga2O3 columns, was amorphous. The film was found to be highly resistive, as is expected for undoped material. This study demonstrates that α-Ga2O3 films can be grown by low temperature ALD and suggests the possibility of a new range of ultraviolet optoelectronic and power devices grown by ALD. The study also shows that scanning electron diffraction is a powerful technique to identify the different polymorphs of Ga2O3 present in multiphase samples.
- semiconducting gallium compounds
- atomic layer epitaxy
- x-ray diffraction
- scanning electron diffraction
Roberts, J. W., Jarman, J. C., Johnstone, D. N., Midgley, P. A., Chalker, P. R., Oliver, R. A., & Massabuau, FC-P. (2018). α-Ga2O3 grown by low temperature atomic layer deposition on sapphire. Journal of Crystal Growth, 487, 23-27. https://doi.org/10.1016/j.jcrysgro.2018.02.014