Analytical model and and qualitative analysis of the interface-trap charge pumping characteristics of MOS structure

A detailed phenomenological description of the charge pumping characteristics of MOS structure, i.e. charge-pumping current vs. gate base level, is introduced. The electron and hole emission and capture processes occurring at the top and bottom levels, and the rise and fall edges of the trapezoidal gate pulses are analyzed. The band gap is divided into characteristic regions for each part of the gate pulse, where particular regions are associated with one dominant generation-recombination process. The carrier emission during the top and bottom levels is also accounted for, which results in a two-part fine structure of the edges of the charge pumping characteristics. The analytical model generalizes present theories, but is still compact and explicit. The model matches well the characteristics computed by rigorous numerical charge pumping model. The predicted fine structure of the curves is observed on experimental characteristics measured on long-channel devices that exhibit small two-dimensional effects. The model also provides a complete understanding of the impact of the charge-potential-feedback effect in all regions of the characteristics in case of high trap density. Finally, an improved formula for the emission level for the non-steady-state trap emission is derived.