Charge distribution in the nitride of MNOS memory devices
The steady state charge distribution for weakly occupied traps is a universal function of position over most of the nitride, with dielectric constant and Frenkel-Poole coefficient α being the only material parameters. The transient charge distribution for constant current pulses is approximated by truncating the steady state distribution and the resulting relation between charge content and its centroid is used to fit experimental data which provides α-values of a reasonable magnitude. A diffusive component of charge motion during application of alternating polarity voltage pulses is identified, and its diffusion coefficient is related to the Frenkel-Poole emission rate from traps.