An analytical model for charge pumping below strong inversion and accumulation

A compact analytical model for charge pumping (CP) is derived. It accounts for emission during the high and low gate bias levels and assumes instantaneous transition edges. This model, which does not apply on the top of the CP curves when using large gate voltage swings, where emission fully proceeds during the transitions edges of the gate signal, applies on all the other regions provided that the transition times of the gate signal are much shorter than the times at steady state biases. Therefore it holds at large bias swings on both edges of Elliot curves and at small bias swings on the whole Elliot curves provided that the interface traps are completely filled [1]. It is compared with the analytical model proposed by Wachnik and Lowney [2] in which emission is not accounted for at all. This model, which holds at Elliot curve maxima when small voltage swings are used, has been shown to be extremely useful for studying interface trap properties [1, 2, 3 and 4]. The CP model proposed primarily, that of Brugler and Jespers [5], is used as a reference. The model derived in this article very satisfactorily fits the experimental curves in the regions of large CP current where it holds. Discrepancies at low current levels are due to the well-known contribution of the transistor source and drain regions or could be due to edge effects. Comparing the different models and the experimental curves allows to evaluate emission and capture during different regions of the gate bias period. The three regions of CP response, depending on the gate voltage swing and involving or not emission and the full filling of the interface traps, are also evidenced.