Ti_0.5Al_0.5O-dielectric AlGaN/GaN/Si metal-oxide-semiconductor heterostructure field-effect transistors by using non-vacuum ultrasonic spray pyrolysis deposition

This work investigates a Ti_0.5Al_0.5O-dielectric Al_0.26Ga_0.74N/GaN metal-oxide-semiconductor heterostructure field-effect transistor (MOS-HFET) grown on a Si substrate, prepared by using a non-vacuum ultrasonic spray pyrolysis deposition (USPD) technique. High dielectric constant (k) was characterized to be 29.1 for a 20-nm thick Ti_0.5Al_0.5O. Hooge coefficient (α_H), low-frequency noise spectra (1/f), high/low frequency capacitance-voltage (C-V), pulse I-V measurements were also performed to investigate the improved passivation and insulation of the MOS-structure. The present MOS-HFET design has exhibited superior improvements of 23% in maximum drain-source current density (I_{DS, max}), 25.1% in drain-source saturation current density at V_GS = 0 V (I_DSS0), 46.3% in two-terminal off-state gate-drain breakdown voltage (BV_GD), and 65% in three-terminal drain-source breakdown voltage (BV_DS), as compared to a reference Schottky-gate HFET device. Enhanced high-frequency, power, and high-temperature performances up to 450 K are also studied.