Enhancement-mode tri-gate GaN MIS-HEMTs with PEALD-AlN/HfO2 dual-gate dielectric

In this study, we demonstrate a PEALD-AlN/HfO2 dual-gate dielectric normally-off GaN high-electron-mobility transistor (HEMT) with a recess-tri-gate architecture. By employing a dual-gate dielectric, devices exhibit a superior interface on the 3D gate structure, yielding a field-effect mobility of ∼1083 cm2/V s. Due to improved channel control from the tri-gate architecture, the device achieves a threshold voltage (VTH) of 1.1 ± 0.1 V, a maximum drain current of 854 ± 10 mA/mm, a specific on-resistance of 0.81 mΩ/cm2, a current on/off ratio of more than eight orders of magnitude, and a subthreshold slope of 103 ± 3 mV/decade. In addition to the excellent DC performance, the Negative Bias Temperature Instability (NBTI) of VTH and interface-trap density of the tri-gate MIS-HEMT were systematically investigated to understand the device’s trapping/detrapping behavior. These results culminate in the strong potential of tri-gate GaN metal–insulator–semiconductor (MIS) HEMTs for high-performance enhancement-mode (E-mode) power device applications, while also providing deeper insight into interface behavior in the tri-gate architecture and the associated trapping dynamics under negative-bias-stress conditions.