Reduction of Fermi-Level Pinning and Controlling of Ni/β-Ga2O3 Schottky Barrier Height Using an Ultrathin HfO2 Interlayer

Achieving precise control of the Schottky barrier height and minimizing Fermi-level pinning effect are crucial factors in designing high-performance Schottky barrier diodes. In this work, the effect of insertion of HfO2 with different cycle numbers on forward current, capacitance, and Ni/HfO2/β-Ga2O3 Schottky barrier height is discussed. First, we observed that Schottky barrier heights extracted from capacitance (ϕBCV) were adjusted in the range of 0.54–1.33 eV, in which it was increased by repeated atomic layer deposition cycles from two to eight. In addition, with increasing HfO2 cycle numbers, the Schottky barrier height became similar to an ideal value, which means the Fermi pinning level effect is reduced. The effects of HfO2 cycle numbers on forward current and on the extracted Schottky barrier height (ϕBJV) were analyzed. We observed that, the forward current was highly dependent on the HfO2 cycle number. Schottky barrier height (ϕBJV) can be controlled easily in a wide range domain from 1.05 to 1.48 eV by increasing HfO2 cycle numbers.