Electrical behavior of β-Ga2O3 Schottky diodes with different Schottky metals

Schottky diodes based on (2¯01) β-Ga2O3 substrates and (010) β-Ga2O3 homoepitaxial layers were formed using five different Schottky metals: W, Cu, Ni, Ir, and Pt. Based on a comparison of the effects of different wet chemical surface treatments on the Ga2O3 Schottky diodes, it was established that a treatment with an organic solvent, cleaning with HCl and H2O2, and rinsing with deionized water following each step yielded the best results. Schottky barrier heights calculated from current–voltage (I-V) and capacitance–voltage (C-V) measurements of the five selected metals were typically in the range of 1.0–1.3 and 1.6–2.0 eV, respectively, and showed little dependence on the metal work function. Several diodes also displayed inhomogeneous Schottky barrier behavior at room temperature. The results indicate that bulk or near-surface defects and/or unpassivated surface states may have a more dominant effect on the electrical behavior of these diodes compared to the choice of Schottky metal and its work function.