| The semiconductor gallium arsenide (GaAs) has many potential advantages over the more widely used semiconductor silicon (Si). These include higher low field mobility, semi-insulating substrates, a direct band-gap, and greater radiation hardness. All these advantages offer distinct opportunities for implementation of new circuit functions or extension of the operating conditions of similar circuits in silicon based technology. However, full exploitation of these advantages has not been realized. This study examines the limitations imposed on conventional GaAs metal-semiconductor field effect transistor (MESFET) technology by deviations of the semi-insulating substrate material from ideal behavior. The interaction of the active device with defects in the semi-insulating GaAs substrate is examined and the resulting deviations in MESFET performance from ideal behavior are analyzed.;A p-well MESFET technology is successfully implemented which acts to shield the active device from defects in the substrate. Improvements in the operating characteristics include elimination of drain current transients with long time constants, elimination of the frequency dependence of g... |