Space charge effects in MNOS memory devices and endurance measurements

The theory of MNOS transistors is developed in an attempt to further understand changes produced by processing variables and endurance stress tests. Since space charge within the oxide and nitride can have considerable effect on the electric fields, a space charge model is presented. Emphasis is on high field direct tunneling from an initial saturated state. The pulse write response is given in terms of observable parameters. Two new parameters are introduced: the center of charge V
TC
and the tunneling threshold V
TT
.