Physics based threshold voltage extraction and simulation for poly-crystalline thin film transistors using a double-gate structure

Abstract

In this work, a two-dimensional potential distribution formulation/model is presented for double-gate poly-crystalline silicon thin film transistors. The work aims at deriving a potential solution for the threshold voltage estimation of the device under consideration. The Green's function approach is adopted for the two-dimensional potential solution. The developed formulation incorporates the effects due to traps and grain boundaries. The existence of short-channel effects and drain-induced barrier-lowering effects can also be seen from the characteristics. A relation to achieve the targeted threshold voltage with the physical gate dielectric thickness, dielectric constant, substrate doping concentration, grain size and drain-source voltage as parameters is also presented. The model is then extended to evaluate drain current performance. The results obtained show an excellent agreement with numerical modelling based on the finite difference method and also a good agreement with simulation results, thus demonstrating the validity of our model.