A Comparative Study on the Electrical Properties of Vertical ($\bar{\sf2}01$) and (010) $\beta$ -Ga2O3 Schottky Barrier Diodes on EFG Single-Crystal Substrates.

This paper reports a comprehensive study on the anisotropic electrical properties of vertical ($\overline {\textsf {2}}01$) and (010) $\beta $ -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 ($\overline {\textsf {2}}01$) and (010) SBDs exhibited on-resistances (${R}_{{ \mathrm{\scriptscriptstyle ON}}}$) of 0.56 and $0.77~\textsf {m}\Omega \cdot \textsf {cm}^{{\textsf {2}}}$ , turn- ON voltages (${V}_{{ \mathrm{\scriptscriptstyle ON}}}$) 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/($\textsf {V}\cdot ~\textsf {s}$), respectively, with an on-current of ~1.3 kA/cm2 and on/off ratio of ~109. The (010) SBD had a larger ${V}_{{ \mathrm{\scriptscriptstyle ON}}}$ 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 ($\overline {\textsf {2}}01$) SBD showed a more uniform SBH distribution. The homogeneous SBH was also extracted: 1.33 eV for the ($\overline {\textsf {2}}01$) 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 ($\overline {\textsf {2}}01$) 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 $\beta $ -Ga2O3 can affect the electrical properties of vertical SBDs and should be taken into consideration when designing $\beta $ -Ga2O3 electronics. [ABSTRACT FROM AUTHOR]