GaN schottky barrier MOSFET using transparent source/drain electrodes for UV-optoelectronic integration

Abstract

We fabricated a normally-off mode n-channel schottky barrier metal oxide semiconductor field effect transistor (SB-MOSFET) with transparent electrodes (ITO, IZO) as source/drain (S/D) contact on a highly resistive GaN layer grown on silicon substrate. Fabricated SB-MOSFET with ITO S/D exhibited as high as 40mA/mm of maximum drain current and a 12mS/mm of maximum transconductance with the threshold voltage of 4.2V, which is far better than that of SB-MOSFET with IZO S/D. The normalized off-current was as low as 10nA/mm. The UV–visible extinction ratio of a MOSFET type UV-sensor was measured over 130 for VDS=5V. ITO was proved as a promising schottky barrier material for GaN MOSFET source and drain not only for the electronic but UV-sensing applications better than IZO for this purpose.