Poly-crystalline Silicon Thin Film Transistor: a Two-dimensional Threshold Voltage Analysis using Green's Function Approach

Abstract

A two-dimensional treatment of the potential distribution under the depletion approximation is presented for poly-crystalline silicon thin film transistors. Green's function approach is adopted to solve the two-dimensional Poisson's equation. The solution for the potential distribution is derived using Neumann's boundary condition at the silicon-silicon dioxide interface. The developed model gives insight into device behavior due to the effects of traps and grainboundaries. Also short-channel effects and drain induced barrier lowering effects are incorporated in the model. The potential distribution and electric field variation with various device parameters is shown. An analysis of threshold voltage is also presented. The results obtained show good agreement with simulated results and numerical modeling based on the finite difference method, thus demonstrating the validity of our model.

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

“…In our analysis, the potential distribution at an unknown common boundary (Neumann's boundary condition) between adjacent regions incorporates these effects. An expression for 2D potential distribution using Green's theorem [20] and after substitution of Green's function [21] solutions is…”

Extraction of Electron Band Mobility in Amorphous Silicon Thin-Film Transistors

“…6) In order to use the a-Si as the display circuit applications, an accurate TFT model is necessary, hence many groups have proposed amorphous silicon TFT models. [7][8][9] In addition, numerical simulations to predict the behavior of TFTs are performed recently. 10) However, the band mobility value used in TFT modeling and numerical simulation is borrowed from the literature rather than obtaining from the experiment due to the difficult process and complex calculations to obtain experimental value of band mobility.…”