Growing high-quality and high-purity beta-phase gallium oxide thin films

Beta-phase gallium oxide has shown potential as an ultrawide-bandgap semiconductor with applications in power electronic devices and short-wavelength optoelectronics. Several fabrication techniques have been investigated for single-crystal thin-film epitaxy of beta-phase gallium oxide, but each face challenges that impede the growth of high-quality and high-purity thin films.

Feng et al. reevaluates one of these methods, namely metalorganic chemical vapor deposition (MOCVD), in an effort to develop better beta-phase gallium oxide thin films. They achieved record-high carrier mobilities for thin films at both room temperature and low temperatures. They also demonstrated record-low extracted compensation concentration, which is critical for controllable tuning of the doping concentration.

The researchers grew the silicon-doped beta-phase gallium oxide thin films on (010)-oriented iron-doped semi-insulating native substrates using MOCVD. They varied the growth temperature, VI/III ratio, and chamber pressure to test the effects of different growth parameters on the final material’s properties. Material characterization via scanning electron microscopy, atomic force microscopy, secondary-ion mass spectroscopy, and X-ray diffraction confirmed the formation of high-quality and high-purity thin films. The thin films exhibited excellent electrical transport properties, with smooth surface morphology at the atomic level and a reasonable growth rate of around one micron per hour.

These findings demonstrate the feasibility of growing beta-phase gallium oxide thin films with MOCVD, an industrially preferred semiconductor epitaxial technology, and the potential of this material for high-power device applications.

Source: “MOCVD homoepitaxy of Si-doped (010) β-Ga₂O₃ thin films with superior transport properties,” by Zixuan Feng, A F M Anhar Uddin Bhuiyan, Md Rezaul Karim, and Hongping Zhao, Applied Physics Letters (2019). The article can be accessed at http://doi.org/10.1063/1.5109678 .