Controlling Characteristics of 4H-SiC(0001) p-Channel MOSFETs Fabricated on Ion-Implanted n-Well

Abstract

Fabricated were 4H-SiC p-channel MOSFETs in two types of ion-implanted n-well regions and in the n-type substrate as a control. Effects of the n-well structure on the electrical properties were investigated. P-channel MOSFETs fabricated in the uniform doped n-well by using multiple ion-implantations showed inferior on-state characteristics to that of the control MOSFET, while those fabricated in the retrograde n-wells by using single-shot ion-implantation without additional implantation to form the surface p-type region indicated improved channel properties. The Vth values were controlled by the impurity concentration and depth of the surface p-type region, and the values of channel mobility were nearly equal to that of the control MOSFET. Good sub-threshold characteristics for the type II devices were demonstrated.