Surface chemical states, electrical and carrier transport properties of Au/ZrO2/n-GaN MIS junction with a high-k ZrO2 as an insulating layer

Highlights: • Chemical composition and depth profile of ZrO₂ films are investigated by XPS. • Au/ZrO₂/n-GaN MIS junction exhibit a high barrier height than the Au/n-GaN MS junction. • Interface state density of MIS junction is lower compared with the MS junction. • Leakage current mechanism is ruled by a PFE mechanism in both MS and MIS junctions. - Abstract: High-k zirconium oxide (ZrO₂) thin insulating layer is deposited on n-type GaN and explored its chemical properties by XPS technique. XPS core level spectra confirms that the formation of ZrO₂ thin film on the n-GaN substrate. Later, the Au/ZrO₂/n-GaN MIS junction is constructed with a ZrO₂ as insulating layer and correlated its electrical properties with the Au/n-GaN MS junction. Results present that a high barrier height (0.94 eV) is obtained for the MIS junction compared with the MS junction (0.73 eV), suggesting the barrier height is altered by the ZrO₂ insulating layer. The estimated interface state density (N_SS) of the MIS junction is lower compared with the MS junction, revealing that the high-k ZrO₂ thin insulating layer decreased N_SS. Results confirmed that the reverse leakage current mechanism is governed by a Poole-Frenkel emission in both MS and MIS junctions.