Effect of inductively coupled plasma etch on the interface barrier behavior of (001) β-Ga2O3 Schottky barrier diode

Abstract

In this study, the (001) β-Ga2O3 surface was dry etched employing the inductively coupled plasma-reactive ion etching (ICP-RIE) system, and Au/Ni/β-Ga2O3 Schottky barrier diodes (SBDs) were fabricated on the etched surface. The impact of ion bombardment on the (001) β-Ga2O3 surface during dry etching and its effect on current-voltage (I–V) characteristics and breakdown voltage was investigated. The forward current at higher bias decreased with increasing temperature due to the fact that the higher temperatures cause them to be less mobile owing to the scattering effects that reduce the on-current. The temperature-dependent I–V characterization of the Au/Ni/β-Ga2O3 SBD revealed a strong temperature dependence of barrier height and ideality factor associated with the barrier height inhomogeneity at the interface between Ni and β-Ga2O3. Analysis of the barrier height inhomogeneities with the assumption of Gaussian distribution of barrier heights confirmed the presence of a double Gaussian barrier distribution having mean barrier heights of 0.71 and 1.21 eV in the temperature range of (83–158) and (183–283 K), respectively. The Richardson constant value obtained from the modified Richardson plot interpreted with the consideration of Gaussian distribution of barrier heights closely matched with the theoretical value of β-Ga2O3. The fabricated Au/Ni/β-Ga2O3 SBD showed consistent breakdown voltage in the range of 670–695 V over repeated measurements with a time interval of 1 min without exhibiting any damage. However, after an initial breakdown voltage measurement, repeating the measurement with a 30 s interval led to an exponential increase in current, leading to the destruction of the device, associated with the low thermal conductivity of the substrate. The results obtained reveal that the ICP-RIE dry etching did not cause significant damage to the surface.