BACKGATING AND LIGHT SENSITIVITY IN GAAS METAL-SEMICONDUCTOR FIELD-EFFECT TRANSISTORS

Three different types of GaAs metal-semiconductor field effect transis tors (MESFET) by employing ion implantation, molecular beam epitaxy (M BE) and low-temperature MBE (LT MBE) techniques respectively were fabr icated and studied in detail. The backgating (sidegating) measurement in the dark and in the light were carried out. For the LT MBE-GaAs buf fered MESFETs, the output resistance R(d) and the peak transconductanc e g(m) were measured to be above 50 k Omega and 140 mS/mm, respectivel y, and the backgating and light sensitivity were eliminated. A theoret ical model describing the light sensitivity in these kinds of devices is given. and good agreement with experimental data is reached.