Improved Ultraviolet Detection and Device Performance of Al2O3-Dielectric In0.17Al0.83N/AlN/GaN MOS-HFETs

Ultraviolet (UV) detection and electrical characteristics of In0.17Al0.83N/AlN/GaN metal-oxide-semiconductor heterostructure field-effect transistors (MOS-HEETs) with Al2O3 gate-dielectric and passivation formed by using ultrasonic spray pyrolysis deposition (USPD) are studied with respect to a conventional Schottky-gate HI-ET. The present MOS-HEET (Schottky-gate HFET) has demonstrated superior spectral responsivity (SR) of 360 (340) A/W at 350 nm at V-GS = 5(3) V and V-DS = 6(7) V, maximum drain-source saturation current density (I-DS,I-max ) of 810.5 (546.6) mA/mm, maximum extrinsic transconductance of (g(m,max)) of 180.4 (221.2) mS/mm, gate-voltage swing (GVS) of 2.4 (0.5) V, on/off current ratio (I-on/I-off) of 5.5 x 10(8) (1.7 x 10(5)), two-terminal off-state gate-drain breakdown voltage (BVGD) of -158.5 (-127) V, three-terminal drain-source breakdown voltage (BVDS) of 162 (83.4) V at V-GS = -10 V, and power-added efficiency (P.A.E.) of 26.3% (16.5%) at 2.4 GHz at 300 K. In addition to the improved device performance, this paper demonstrates, for the first time, the UV sensing based on an InAlN/AlN/GaN MOS-HFET design.