Improved Electrical and Deep-UV Sensing Characteristics of Al₂O₃-Dielectric AlGaN/AlN/SiC MOS-HFETs

Improved electrical and deep-UV sensing characteristics of Al2O3-dielectric Al0.75Ga0.25N/n-AlxGa1-xN/Al0.75Ga0.25N/AlN metal-oxide-semiconductor hetero-structure field-effect transistors (MOS-HFETs), grown on a SiC substrate, with an AlGaN ultra-widegap channel design are investigated. 30 nm thick high-k Al2O3 was deposited as both the gate oxide and surface passivation layer by using a non-vacuum ultrasonic spray pyrolysis deposition (USPD) method. Improved device characteristics, including maximum drain-source current density (I DS,max) of 130.1 mA mm-1, maximum extrinsic transconductance (g m,max) of 11.8 mS mm-1, on/off-current ratio (I on /I off ) of 1.4 107, gate-voltage swing (GVS) linearity of 5.8 V, two-terminal off-state gate-drain breakdown voltage (BV GD ) of -404 V, and three-terminal on-state drain-source breakdown voltage (BV DS ) of 364 V at 300 K are obtained for the present MOS-HFET. The device has demonstrated high spectral responsivity (SR) of 737 A W-1 under 250 nm deep-UV radiation.