Charge retention in metal--oxide--semiconductor capacitors on SiC used as nonvolatile-memory elements

Abstract

In this letter, the possibility of using metal-oxide-semiconductor capacitors on SiC as nonvolatile random-access memory elements has been experimentally investigated. Because of the wide energy gap and the very low minority-carrier generation rate in SiC, it should be possible to achieve very long retention times. The investigations show that charge leakage through the gate oxide may prevent the use of SiC metal-oxide-semiconductor (MOS) capacitors as memory elements. Importantly, the experiments demonstrate that both the charge leakage and carrier-generation rate are low in the case of nitrided SiO2-SiC interfaces. The retention time extrapolated to room temperature is in the order of 109 years for the case of MOS capacitors on 4H-SiC, which is approximately equal to the theoretical limit.