Abstract :
Comparative studies for TiO2-passivated Al0.25Ga0.75N/GaN heterostructure FETs (HFETs) and TiO2-dielectric MOS-HFETs using nonvacuum ultrasonic spray pyrolysis deposition technique are made. Optimum device performances are obtained by tuning the layer thickness of TiO2 to 20 nm. High relative permittivity (k) of 53.6 and thin effective oxide thickness of 1.45 nm are also obtained. Pulse-IV, Hooge coefficient (αH), Transmission Electron Microscopy, and atomic force microscope have been performed to characterize the interface, atomic composition, and surface flatness of the TiO2 oxide. Superior improvements for the present TiO2dielectric MOS-HFET/TiO2-passivated HFETs are obtained, including 47.6%/23.8% in two-terminal gate-drain breakdown voltage (BVGD), 111%/22.2% in two-terminal gate-drain turnON voltage (VON), 47.9%/39.4% in ON-state breakdown (BVDS), 12.2%/10.2% in drain-source current density (IDS) at VGS = 0 V (IDSS0), 27.2%/11.7% in maximum IDS (IDS,max), 3/1-order enhancement in ON/OFF current ratio (ION/IOFF), 58.8%/17.6% in gate-voltage swing linearity, 25.1%/13.2% in unity-gain cutoff frequency (fT), 40.6%/24.7% in maximum oscillation frequency (fmax), and 33.8%/15.6% in power-added efficiency with respect to a Schottky-gated HFET fabricated on the identical epitaxial structure. The present MOS-HFET has also shown stable electrical performances when the ambient temperature is varied from 300 to 450 K.
Keywords :
III-V semiconductors; aluminium compounds; atomic force microscopy; current density; gallium compounds; high electron mobility transistors; permittivity; titanium compounds; transmission electron microscopy; vapour deposition; wide band gap semiconductors; Al0.25Ga0.75N-GaN; Hooge coefficient; Schottky-gated HFET; Si; TiO2; atomic composition; atomic force microscopy; dielectric MOS-HFET; drain-source current density; epitaxial structure; gate-voltage swing linearity; maximum oscillation frequency; metal oxide semiconductor-heterostructure field effect transistor; nonvacuum ultrasonic spray pyrolysis deposition technique; on-off current ratio; on-state breakdown; power-added efficiency; pulse-IV; relative permittivity; transmission electron microscopy; two-terminal gate-drain breakdown voltage; two-terminal gate-drain turn on voltage; unity-gain cutoff frequency; Aluminum gallium nitride; Dielectrics; Gallium nitride; HEMTs; Logic gates; MODFETs; Passivation; AlGaN/GaN/Si; MOS-heterostructure FET (HFET); TiO₂; TiO2; high temperature; passivation; ultrasonic spray pyrolysis deposition (USPD); ultrasonic spray pyrolysis deposition (USPD).;
