Experimental and theoretical investigations on short-channel effects in 4H-SiC MOSFETs

In this paper, a fundamental investigation on short-channel effects (SCEs) in 4H-SiC MOSFETs is given. Planar MOSFETs with various channel lengths have been fabricated on p-type 4H-SiC (0001), (0001) and (1120) faces. In the fabricated MOSFETs, SCEs such as punchthrough behavior, decrease of threshold voltage, deterioration of subthreshold characteristics, and saturation of transconductance occur by reducing channel length. The critical channel lengths below which SCEs occur are analyzed as a function of p-body doping and oxide thickness by using device simulation. The critical channel lengths obtained from the device simulation is in good agreement with the empirical relationship for Si MOSFETs. The critical channel lengths in the fabricated SiC MOSFETs are slightly longer than simulation results. The dependence of crystal face orientations on SCEs is hardly observed. Impacts of interface charge on the appearance of SCEs are discussed.