Field-enhanced space-charge-limited hole currents in thin-oxide MNOS varactors

This paper describes the results of an investigation of hole currents in the thin-oxide metal-silicon nitride-silicon dioxide-silicon (MNOS) varactor structure. Deviations from the predictions of Poole-Frenkel theory were noted. The results were analyzed using the calculations of Murgatroyd for space-charge-limited (SCL) flow, suitably modified to account for a threshold of SCL current due to the oxide potential barrier. The result is shown to agree with experiment over approximately six decades of current while traditional space-charge-free Poole-Frenkel theory does not.