Thermal stability of single crystalline alpha gallium oxide films on sapphire substrates

Abstract High quality single crystalline alpha gallium oxide (α‐Ga 2 O 3 ) films, as highlighted by the X‐ray diffraction ω‐scan full‐width at half maximum of as small as 30 arcsec, were prepared by the mist chemical vapor deposition (CVD). The quality of the film was markedly dependent of the carrier gas flow rate, so we need careful attention for the optimum growth conditions. The thermal stability of α‐Ga 2 O 3 films was investigated by studying their thermal stability under thermal annealing in terms of the structural and optical properties. It was found that α‐Ga 2 O 3 films grown at 470 °C are stable until 550 °C, but are gradually transformed to β‐Ga 2 O 3 over 600 °C. Finally, β‐Ga 2 O 3 films only existed at 700 °C. So the device processes for α‐Ga 2 O 3 should be done below 550 °C to avoid phase transformation. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)