UV Responsive Characteristics of n-Channel Schottky Barrier MOSFET with ITO as Source/Drain Contacts

Abstract

We fabricated a schottky barrier metal oxide semiconductor field effect transistor(SB-MOSFET) by applying indium-tin-oxide(ITO) to the source/drain on a highly resistive GaN layer grown on a silicon substrate. The MOSFET, with 10 m gate length and 100 m gate width, exhibits a threshold gate voltage of 2.7 V, and has a sub-threshold slope of 240 mV/dec taken from the I DS -V GS characteristics at a low drain voltage of 0.05 V. The maximum drain current is 18 mA/mm and the maximum transconductance is 6 mS/mm at V DS =3 V. We observed that the spectral photo-response characterization exhibits that the cutoff wavelength was 365 nm, and the UV/visible rejection ratio was about 130 at V DS = 5 V. The MOSFET-type UV detector using ITO, has a high UV photo-responsivity and so is highly applicable to the UV image sensors.