Current transport properties of Pt/n-GaN Schottky diodes with ZnO interlayers

In this work, atomic layer deposition (ALD) was used to grow 20-nm thick ZnO interlayers (IL) on a GaN substrate at 150 and 200 °C and the current transport mechanisms of vertical Pt/ZnO/n-GaN Schottky diodes were investigated. A high density of surface state was observed for the ZnO layer grown at 200 °C. An analysis of the forward current–voltage (I–V) data considering various transport mechanisms demonstrated that the thermionic emission and the tunneling components attributed to the total current for the ZnO layer grown at 150 °C. In contrast, it was observed that the tunneling component mainly caused the current conduction in the ZnO layer grown at 200 °C. Additionally, an analysis of the reverse I–V characteristics exhibited a high density of surface defects on the ZnO layer grown at 200 °C. This study demonstrated that the ALD growth temperature of ZnO IL significantly affects the I–V characteristics of GaN Schottky diodes.