Structural and electrical properties of heteroepitaxial (111)Fe₃O₄/(0001)GaN Schottky junction

We investigated the structural and electrical properties of the half-metallic oxide Fe₃O₄ film grown on an n-type semiconducting gallium nitride GaN. X-ray diffraction and transmission electron microscopy analyses confirmed the heteroepitaxial growth of the (111) Fe₃O₄ film on (0001) GaN with a clear interface. The current–voltage measurement for the Fe₃O₄/GaN heterojunction indicated a strong temperature dependence of the Schottky diode behavior. At room temperature, the Fe₃O₄/GaN heterojunction exhibited a weak diode-like behavior for the bias-voltage sweep. However, as the temperature decreased from room temperature to 30 K, the current in negative-bias voltages decreased significantly, but its change in the positive bias regions was small. Thus, the rectification ratio increased by ∼10⁴ times, while the barrier height decreased and the ideality factor increased. The barrier height inhomogeneities at the interface could be an origin for such distinctive temperature dependences of barrier height and ideality factor.