Interfacial and electrical characteristics of tetragonal HfO 2 /Al 2 O 3 multilayer grown on AlGaN/GaN

We report the study of HfO 2 /Al 2 O 3 multilayer (HAOM) that is deposited on AlGaN/GaN heterostructure by plasma enhanced atomic layer deposition (PEALD). The properties and passivation effect of HAOM, sole Al 2 O 3 and HfO 2 films were investigated. After high-temperature rapid thermal annealing (RTA) of 850 °C, the formation of tetragonal phase in HAOM is presented. Al incorporates into HfO 2 layers during RTA, which facilitates the formation of tetragonal HfO 2 . The HAOM film reveals an effective dielectric constant of ~ 30.2, a critical electric field of 7.6 MV/cm and leakage of only 6.8 × 10 −4 mA/cm 2 at gate bias of |V g − V fb | = 10 V. The HAOM insulating layer is shown to be effective in suppressing leakage current. In particular, the HAOM MIS diode current is reduced by both 6 orders of magnitude at negative bias of − 10 V and forward bias of 1.5 V compared with a conventional Schottky diode.