TiO2-Dielectric AlGaN/GaN/Si Metal-Oxide-Semiconductor High Electron Mobility Transistors by Using Nonvacuum Ultrasonic Spray Pyrolysis Deposition

High-k TiO
₂
-dielectric Al
_0.25
Ga
_0.75
N/GaN metal-oxide-semiconductor high-electron mobility transistors (MOS-HEMTs) grown on Si substrates by using nonvacuum ultrasonic spray pyrolysis deposition technique are reported for the first time. The effective oxide thickness is 1.45 nm with layer thickness/dielectric constant of 20 nm/53.6. Pulse I-V and low-frequency noise spectra (1/f) are conducted to characterize the interface property. The gate leakage current I
_GD
is decreased by three orders at V
_GD
= -50 V as compared with a reference Schottky-gate device. Superior device characteristics are achieved for the present MOS-HEMT (Schottky-gate HEMT) for the gate dimensions of 1 μm × 100 μm including drain-source current density I
_DS
at V
_GS
= 0 V (I
_DSS0
) of 384 (342) mA/mm, maximum I
_DS
(I
_DS
,
_max
) of 650 (511) mA/mm, maximum extrinsic transconductance (g
_m
,
_max
) of 107 (110) mS/mm, two-terminal gate-drain breakdown voltage (BVGD) of -155 (-105) V, turn-ON voltage (VON) of 3.8 (1.8) V, ON-state breakdown (BVDS) of 139 (94) V, gate-voltage swing of 2.7 (1.7) V, and ON/OFF current ratio (I
_ON
/I
_OFF
) of 4.5 x 10
⁵
(3.5 x 10
²
).