Microwave characteristics of GaAs MESFET with optical illumination

Abstract

We fabricated 1x240 mu m(2) GaAs MESFET's and investigated their microwave characteristics under optical illumination with varying optical power density from 1.6mW/cm(2) to 472mW/cm(2). Typical current gain cut-off frequency(fT) and maximum frequency of oscillation(f(max)) of fabricated devices were 6.6GHz and 13.6GHz, respectively, at V-ds=3.0V and V-gs=-0.25V without optical illumination. Under 157mW/cm(2) of optical illumination at the same bias, however, fT and f(max) were increased to 9.5GHz and 15.3GHz, respectively. Extracted device parasitics with optical illumination are also reported.