Comparison of charge–retention times in n- and p-type 4H–SiC MOS capacitors as non-volatile memory elements

Abstract

Retention of non-equilibrium charge in MOS capacitors on p-type 4H SiC with thermally grown nitrided gate oxides have been experimentally investigated. The reasons of short charge–retention time in this type of capacitors compared to n-type MOS capacitors have been identified: supply of minority carriers from the perimeter of the capacitors contributes to fast creation of the inversion layer. A negatively biased shielding ring has been employed to eliminate the lateral supply of minority carriers (electrons) and to enable measurement of the effective generation rate.