Photovoltage and channel conductance analysis of buried gate MESFET with modulation frequency

This paper provides new insight into the cause of photovoltage generation and channel conductance variation in an ion-implanted buried-gate GaAs MESFET with front side illumination. When optical fiber with modulated frequency falls on the device, flow of charge carriers changes corresponding to the change in the wavelength and frequency of incident light. The photo voltage is developed due to the transport of holes across the Schottky junction .The data suggest that the magnitude of photo voltage increases, and as a result, there are more uncovered ionic charges in the space charge region toward the drain-side of the gate. This analysis including surface states and the ion implanted buried-gate process. The access charge density at the drain-side of the depletion induces opposite charges in the gate electrode. Consequently, it gives forward biasing to the Schottky barrier gate which increases with increasing values of Ids. As a result, the modulation of channel conductance and photo-voltage characteristics due to the buried-gate GaAs MESFET becomes high effective. The results indicate very good performance of the device compared to other devices like MESFET under back illumination and MESFET with front illumination having surface gate.