The Effects of Annealing on the Switching Characteristics of an Ion-Implanted Silicon MESFET

Abstract

The effects of annealing on the switching characteristics of an ion implanted Si MESFET are considered. The gate-source and the gate-drain capacitances and the drain-source resistance are calculated in the region below pinchoff in the post-implanted annealing condition. It is observed that the capacitances decrease and the resistance increases compared to the case where diffusion of impurity ions due to annealing is not considered. Dopants of P, B, As, Sb, Ga, and Al have been chosen for the calculation. The delay time is found to be mostly unaffected due to annealing. The capacitances in the region above pinchoff show an increase as a result of annealing in the enhancement device compared to the case when diffusion is not taken into account. These capacitances are mainly due to the sidewalls of the space-charge region and are dependent on the threshold voltage, which decreases at higher anneal temperatures in the enhancement mode. © 1989 IEEE