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 HfO 2 with different cycle numbers on forward current, capacitance, and Ni/HfO 2 /β-Ga 2 O 3 Schottky barrier height is discussed. First, we observed that Schottky barrier heights extracted from capacitance (ϕ B CV ) 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 HfO 2 cycle numbers, the Schottky barrier height became similar to an ideal value, which means the Fermi pinning level effect is reduced. The effects of HfO 2 cycle numbers on forward current and on the extracted Schottky barrier height (ϕ B JV ) were analyzed. We observed that, the forward current was highly dependent on the HfO 2 cycle number. Schottky barrier height (ϕ B JV ) can be controlled easily in a wide range domain from 1.05 to 1.48 eV by increasing HfO 2 cycle numbers.