Electrical properties of Au/Bi_0.5Na_0.5TiO ₃-BaTiO₃/n-GaN metal-insulator-semiconductor (MIS) structure

We investigated the electrical properties of solution processed high-k Bi_0.5Na_0.5TiO₃ (BNT)-BaTiO₃ (BT) on n-GaN with Au electrode. Higher barrier height is obtained for Au/BNT-BT/n-GaN structure compared to Au/n-GaN structure. Thin interfacial layer is formed in between BNT-BT and n-GaN confirmed by TEM results. The interface state density of Au/BNT-BT/n-GaN structure is lower than that of Au/n-GaN structure due to the existence of interfacial layer (Ga-O) at the interface. It is observed that the frequency dispersion is decreased in the Au/BNT-BT/n-GaN structure. Poole-Frenkel mechanism is found to dominate the reverse leakage current in both Au/n-GaN and Au/BNT-BT/n-GaN structures.