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

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 (NSS) of the MIS junction is lower compared with the MS junction, revealing that the high-k ZrO2 thin insulating layer decreased NSS. Results confirmed that the reverse leakage current mechanism is governed by a Poole-Frenkel emission in both MS and MIS junctions.