Investigation of Interlayer Dielectric in BaTiO₃/III-Nitride Transistors

In this study, the impact of varying the thickness of the Al2O3 interlayer dielectric on the electrical characteristics of BaTiO3/III-nitride transistors is investigated. In the findings, it is revealed that a minimum thickness of 8 nm for the Al2O3 layer is crucial to maintain high device performance and protect against sputtering-induced damage during BaTiO3 deposition. The fabricated BaTiO3/Al2O3/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 Omega 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 Al2O3 thickness demonstrates excellent agreement between theoretical and experimental values for effective mobility, achieving a value of 1188 cm(2) V-1 center dot s at a 2D electron gas density of 10(13) cm(-2). Furthermore, in the study, it is confirmed that increasing the Al2O3 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 Al2O3 thickness in optimizing the electrical characteristics and overall performance of BaTiO3/III-nitride transistors are highlighted.