AlGaN/GaN MOS-HEMTs with TiO2 gate dielectric by using non-vacuum ultrasonic spray pyrolysis deposition

AlGaN/GaN metal-oxide-semiconductor high electron mobility transistors (MOS-HEMTs), grown on the Si substrate, with high-k TiO₂ gate dielectric (k = 53.6) formed by using non-vacuum ultrasonic spray pyrolysis deposition (USPD) method has been investigated. Pulse I-V and low-frequency noise spectra (1/f) are conducted to characterize the interface property. Enhanced device performances have been accomplished for the devised MOS-HEMT (Schottky-gate HEMT) for the gate dimensions of 1 × 100 μιη², 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 (gm, max) of 107 (110) mS/mm, two-terminal gate-drain breakdown voltage (BV_GD) of -155 (-105) V, turn-on voltage (V_on) of 3.8 (1.8) V, on-state breakdown (BV_DS) of 139 (94) V, gate-voltage swing (GVS) of 2.7 (1.7) V, and on/off current ratio (I_on/I_off) of 4.5 × 105 (3.5 × 102). Consequently, the present MOS-HEMT design by using the cost-effective USPD method is suitable for high-power RF circuit applications.