Design and fabrication of field-plated normally off β-Ga₂O₃ MOSFET with laminated-ferroelectric charge storage gate for high power application

In this work, an enhancement-mode (E-mode) β-Ga₂O₃ metal-oxide-semiconductor field-effect transistor (MOSFET) has been achieved by incorporating a laminated-ferroelectric charge storage gate (L-FeG) structure [Al₂O₃/HfO₂/Al₂O₃/Hf_0.5Zr_0.5O₂ (HZO) of 10/5/2/16 nm]. The band diagram between L-FeG dielectrics (Al₂O₃, HfO₂, and HZO) and β-Ga₂O₃ was determined by x-ray photoelectron spectroscopy. After applying a gate pulse with an intensity of +18 V and width of 1 ms, the saturation current of the E-mode device was measured to be 23.2 mA/mm, which shows a negligible current reduction compared to that of 22.1 mA/mm in a depletion- (D-) mode device. In addition, the threshold voltage (V_TH) is only shifted by 2.76% and 2.18%, respectively, after applying the gate stress and gate-drain stress of 15 V for 10⁴ s. Meanwhile, a high breakdown voltage of 2142 V and specific on-resistance (R_ON,sp) of 23.84 mΩ·cm² were also achieved, which correspond to a state-of-art high power figure of merit of 192.5 MW/cm², showing the great potential of combing the ferroelectric gate stack and lateral Ga₂O₃ MOSFET as next generation power devices.