Analytical theory of two-dimensional charge sheet model for short channel MOSFETs under non linear charge control

Abstract

An analytical theory of two-dimensional charge sheet model of short channel IGFETs under non-linear charge control which geometrically takes into account the two-dimensional edge effect is developed. This theory includes the effects of non-uniform doping and uses the charge sheet model approach. Since the diffusion current plays an important role in subthreshold and saturation regions, the model also takes it into account along with the drift current. The model thus proposed is more accurate than the earlier models as it includes the effects of diffusion and leads to an exact analytical expression for the device current. The results obtained are compared with those of uniform doping. It is found that the current magnitude starts out greater for non-uniform doping and as the gate voltage is increased, the increase in current slows down and approaches to that of uniform doping.