Analysis of Anomalous Charge-Pumping Characteristics on 4H-SiC MOSFETs

Anomalous charge-pumping characteristics of 4H-silicon carbide (SiC) MOSFETs were analyzed. Charge-pumping measurements of n- and p-channel 4H-SiC MOSFETs with and without NO annealing were performed. Measurements using various pulse fall times revealed that the geometric component exists in the n-channel 4H-SiC MOSFETs and is particularly large in the unannealed n-channel 4H-SiC MOSFETs with low channel mobility. In addition, influence of interface states on the charge-pumping curves is significant in the unannealed 4H-SiC MOSFETs. The charge-pumping curves are distorted by these two nonideal effects, making the analysis of the charge-pumping curves difficult. A sufficiently long pulse fall time, which is on the order of 1-10 mus for the n-channel 4H-SiC MOSFETs with a 10-mum gate length, is required to minimize the effect of the geometric component.