Analysis of surface states of gallium arsenide metal semiconductor field-effect transistors using drain current transients under light illumination

Characteristics of charge trapping at surface states of gallium arsenide me tal semiconductor held-effect transistors (GaAs MESFETs) are analyzed using drain current transients under light illumination. Accurate trap density i s obtained by classifying the transient into two components: one resulting from thermal emission and the other from light illumination. A slight decre ase in delay time is observed under infrared light illumination having the photon energy lower than the band gap of GaAs, Pulse light illumination ind icates an increase in charge trapping under the illumination during gate-of f period.