Gate Capacitance and Conductance-Voltage Characteristics of Vertical 4H-SiC MOSFETs

We have characterized gate capacitive and conductive behaviors of commercial Si and 4H-SiC vertical MOSFETs that have never been reported previously. The characteristics and possible physical reasons are determined and corroborated with device simulations. The measurements were carried out on different 1200V 4H-SiC MOSFETs from several vendors by impedance analyzer. Typical C-V characteristics of gate-controlled diodes are observed in those MOSFETs, while several conductance peaks are also captured in G-V measurements. These conductance peaks, reproduced with numerical simulations, are not necessarily related to the behavior of any interface states at the gate oxide/ 4H-SiC interface.

Performance analysis of ultrathin junctionless double gate vertical MOSFETs

The main challenge in MOSFET minituarization is to form an ultra-shallow source/drain (S/D) junction with high doping concentration gradient, which requires an intricate S/D and channel engineering. Junctionless MOSFET configuration is an alternative solution for this issue as the junction and doping gradients is totally eliminated. A process simulation has been developed to investigate the impact of junctionless configuration on the double-gate vertical MOSFET. The result proves that the performance of junctionless double-gate vertical MOSFETs (JLDGVM) are superior to the conventional junctioned double-gate vertical MOSFETs (JDGVM). The results reveal that the drain current (ID) of the n-JLVDGM and p-JLVDGM could be tremendously enhanced by 57% and 60% respectively as the junctionless configuration was applied to the double-gate vertical MOSFET. In addition, junctionless devices also exhibit larger ION/IOFF ratio and smaller subthreshold slope compared to the junction devices, implying that the junctionless devices have better power consumption and faster switching capability.