Dependence of charge-retention time in 4H-SiC MOS capacitors on interface defects and applied gate voltage

In this paper, we have investigated factors that affect the charge-retention time in 4H-SiC MOS capacitors, used as nonvolatile random-access memory elements. The charge-retention time is extracted from high temperature capacitance-transient (C-t) measurements. The SiC-SiO₂ interface traps, that relate to gate oxide processing conditions and the applied gate voltage (V_G) as the main operation-related parameter are investigated. It is found that (1) the charge-retention time depends strongly on the interface-trap density and (2) the time is shortened when the applied gate voltage is reduced.