A Comparative Study on the Electrical Properties of Vertical (sf201) and (010) β-Ga₂O₃ Schottky Barrier Diodes on EFG Single-Crystal Substrates

This paper reports a comprehensive study on the anisotropic electrical properties of vertical (2 01) and (010) β-Ga₂O₃ Schottky barrier diodes (SBDs). The devices were fabricated on single-crystal substrates grown by an edge-defined film-fed growth method. The temperature-dependent current-voltage (I-V) and capacitance-voltage (C-V) characteristics were systematically measured, analyzed, and compared. The (2 01) and (010) SBDs exhibited on-resistances (R ON) of 0.56 and 0.77m Ω cm 2, turn-ON voltages (V N) of 1.0 and 1.3 V, Schottky barrier heights (SBHs) of 1.05 and 1.20 eV, electron mobilities of 125 and 65 cm²/( V s), respectively, with an on-current of 1.3 kA/cm² and on/off ratio of 10⁹. The (010) SBD had a larger V ON and SBH due to anisotropic surface properties (i.e., surface Fermi level pinning and band bending), as supported by X-ray photoelectron spectroscopy measurements. Temperature-dependent I-V also revealed the inhomogeneous nature of the SBH in both devices, where the (2 01) SBD showed a more uniform SBH distribution. The homogeneous SBH was also extracted: 1.33 eV for the (2 01) SBD and 1.53 eV for the (010) SBD. The reverse leakage current of the devices was well described by the two-step trap-assisted tunnelingmodel and the 1-D variable range hopping conduction model. The (2 01) SBD showed a larger leakage current due to its lower SBH and/or smaller activation energy, and thus a smaller breakdown voltage. These results indicate that the crystalline anisotropy of β-Ga₂O₃ can affect the electrical properties of vertical SBDs and should be taken into consideration when designing β-Ga₂O₃ electronics.