Temperature-dependent Schottky diode behavior of Ni Schottky contacts to α-Ga2O3 film epitaxially grown on sapphire substrate

We fabricated Ni Schottky contacts on alpha-Ga2O3 epitaxial layers grown on a c-plane sapphire substrate and explored their current-voltage (I-V) characteristics dependence on temperature spanning over a wide temper-ature range of 100-425K. The Ni/alpha-Ga2O3 Schottky diode displayed excellent rectification, exhibiting a high barrier height of 1.39 eV, a low leakage current of the order 10-12 A, and a breakdown voltage of 215 V at room temperature. The reverse leakage current was confined within an order of magnitude over the entire measured temperature range, indicating the thermal stability of the diode. A large ideality factor of 1.20 attained at room temperature clearly indicates the diode behavior deviation from the ideal thermionic emission theory. The I-V characteristics revealed that the barrier height and ideality factor shows strong temperature dependence, indi-cating the existence of barrier inhomogeneity at the Schottky interface. An analysis of the barrier inhomogeneity using the thermionic emission with the assumption of a Gaussian barrier height distribution implies the pre-vailing double Gaussian barrier height distribution in the Ni/alpha-Ga2O3 Schottky diode with a transition at 250 K. The Richardson constant derived from the modified Richardson plot, evaluated by assuming the barrier height Gaussian distribution, was close to the theoretical Richardson constant of alpha-Ga2O3.

Automated summary

We investigated Ni Schottky contacts on alpha-Ga2O3 epitaxial layers and studied their current-voltage characteristics at temperatures ranging from 100 to 425 K. The Ni/alpha-Ga2O3 Schottky diode showed excellent rectification with a high barrier height of 1.39 eV, a low leakage current of around 10-12 A, and a breakdown voltage of 215 V at room temperature. The temperature dependence of the barrier height and ideality factor indicated the presence of barrier inhomogeneity at the Schottky interface, with a transition occurring at 250 K.