Investigation of Interlayer Dielectric in BaTiO₃/III‐Nitride Transistors

In this study, the impact of varying the thickness of the Al 2 O 3 interlayer dielectric on the electrical characteristics of BaTiO 3 /III‐nitride transistors is investigated. In the findings, it is revealed that a minimum thickness of 8 nm for the Al 2 O 3 layer is crucial to maintain high device performance and protect against sputtering‐induced damage during BaTiO 3 deposition. The fabricated BaTiO 3 /Al 2 O 3 /AlGaN/GaN high electron mobility transistors exhibit exceptional electrical properties, including a maximum current density of 700 mA mm −1 , an on‐resistance of 5 Ω mm, an I ON / I OFF ratio of 10 7 , a subthreshold slope of 119 mV dec −1 , and significantly reduced gate leakage current. The devices with the optimal 8 nm Al 2 O 3 thickness demonstrates excellent agreement between theoretical and experimental values for effective mobility, achieving a value of 1188 cm 2 V −1 ·s at a 2D electron gas density of 10 13 cm −2 . Furthermore, in the study, it is confirmed that increasing the Al 2 O 3 thickness also improves the quality of interface charge density, as evidenced by the results obtained from capacitance–voltage measurements. In these findings, the critical role of controlling the Al 2 O 3 thickness in optimizing the electrical characteristics and overall performance of BaTiO 3 /III‐nitride transistors are highlighted.