Vertical Schottky barrier diodes of α-Ga2O3 fabricated by mist epitaxy

Ga2O3 possesses promising potential for power devices, supported by wide band gap of 4.9 eV (β-phase) and 5.3 eV (α-phase), as successfully demonstrated by Schottky barrier diodes (SBDs) and MOSFETs on β-Ga₂O₃ substrates. However, in terms of future industrial applications, cost and availability of large-scale β-Ga₂O₃ wafers as well as throughput of epitaxy technique might be issues to be overcome. We have proposed the use of sapphire substrates and mist epitaxy techniques for the growth, resulting in high-quality corundum-structured α-Ga₂O₃ as evidenced by the small FWHM values of X-ray diffraction rocking curves, for example, 23 arcsec. With the use of novel precursors and growth conditions, carbon contamination in the epilayers, which has been the severe problem in MOCVD, was below the detectable limit of SIMS. The surface was atomically flat with step and terrace structures, as shown by the AFM image. Excellent uniformity on 4-inch^φ sapphire wafer, lateral SBD, and MESFET have successively been demonstrated.