Properties of Ga2O3-based (Inx Ga1–x)2O3 alloy thin films grown by molecular beam epitaxy



A series of Ga2O3-based (Inx Ga1–x)2O3 alloy thin films have been grown on c-plane sapphire substrates with a thin Ga2O3 buffer layer by plasma-assisted molecular beam epitaxy. At growth temperatures of 700 °C and higher, even with a slight inclusion of In2O3 to Ga2O3, for example, the film of (In0.08Ga0.92)2O3, exhibited a rough surface and degraded transmission spectrum resulting from phase separation of In2O3. Due to low temperature growth at 600 °C, however, the phase separation was suppressed for the In composition up to 35%, which was confirmed by X-ray diffraction measurement, and the films exhibited high transmittance over 85% with sharp absorption edges. The bandgap could be tuned form 5.0 to 4.0 eV. The results encourage the application of (Inx Ga1–x)2O3 thin films in short-wavelength optical devices. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)