DOI: 10.25442/hku.30009205
title: <i>Supporting data for “Collaborative TCAD-Numerical Optimization for</i><i>Off-State Current Modeling in a-Si:H TFTs”</i>

description: Abstract: The main research content of this thesis is physical model calibration and new model construction for the off-state leakage current in Hydrogenated Amorphous Silicon (a-Si:H) thin-film transistors. The article first introduces some concepts regarding a-Si:H TFTs, including: the manufacturer of the devices used in this thesis, the working principle of TFTs, their electrical char acteristics, characterization methods, applications, etc. Proceeding from these aspects, it briefly summarizes TFT development, and provides brief analysis and generalization of existing research on tunneling effect models within the off-state leakage current. Then, this thesis investigates the issue of abnormal rise in the off-state leakage current of the TFT device under high drain volt age, under high reverse gate voltage. After this, here actually truly for the f irst time, a semi-empirical Band-to-Band Tunneling (BBT) physical model formula, modified by experimental data and based on the a-Si:H TFT device, is proposed. Finally, supplemented by numerical calculations based on two generation mechanisms of off-state current ( 𝐼𝑜𝑓𝑓), and using an Artificial In telligence (AI) optimizer independently developed by the subject group within Technology Computer-Aided Design (TCAD) simulation, this work tries to tentatively optimize the parameter selection for off-state simulation of a-Si:H TFT devices. This thesis first, after introducing the basic Hydrogenated Amorphous Silicon TFT related knowledge, explores the influences of the parameters and variables in its TCAD simulation on the TFT characterization curves. Includ ing material properties, physical models, physical model parameters, defects at different locations, fixed charges, and other factors on the output characteristic curves and transfer characteristic curves. Immediately following, this thesis, centering around the problem of the a-Si:H TFT’s off-state leakage current rise not matching experimental mea surements, unfolds the research. First it introduces the concept of tunneling current and introduces how existing research explains the parameter physical meaning of tunneling current, as well as shows parts of the physical models related to leakage current in TCAD software. Afterwards, this thesis takes the band-to-band tunneling physical model parameters used by the curves corre sponding to different drain voltages and takes different values, and inversely calibrates the parameters from experiments. Finally it obtains a semi-empirical new-style band-to-band tunneling formula. After the foundational concepts and using physical model parameter cali bration to deduce semi-empirical formulas, this thesis begins to make an intro duction and subdivision of the principles of TFT off-state current (𝐼off), mainly focusing on carriers in the energy band moving via band-to-band tunneling, trap-assisted tunneling, and also introduces the specialized leakage current terminology GIDL (Gate Induced Drain Leakage Current) applied to more complex devices such as MOSFETs and TFTs. Then, based on this founda tion, using MATLAB’s numerical computation, calculates the optimization coefficients for the sum of leakage currents. Finally, this thesis utilizes the TCAD AI optimizer self-developed by the affiliated research group, demonstrates the parameter selection for off-state simulation of Hydrogenated Amorphous Silicon TFT devices. Keywords: Amorphous Silicon, Hydrogenated Amorphous Silicon, Thin Film Transistor, Off-State Current, GIDL, Leakage Current 𝐼off, Band-to-Band Tunneling Model, Trap-Assisted Tunneling Model, Poole-Frenkel Effect, SRH Recombination, Numerical Computation, TCAD, AI