臺灣博碩士論文加值系統

隨著非晶矽的不斷發展與多方面的被應用，介於非晶矽及多晶矽之間的
微晶矽也開始受到重視．由於微晶矽薄膜電晶體有可能取代現在已經被廣
泛運用的非晶矽薄膜電晶體，因此需要有個能夠對微晶矽薄膜電晶體特性
作分析及預測的工具．所以我們建立了微晶矽薄膜電晶體電流電壓特性的
電腦數值模擬模型． 由於影
響微晶矽與非晶矽特性的受限態兩者相近似，因而可以將描述非晶矽的受
限態的模型修改成為描述微晶矽的受限態的模型．考慮微晶矽與非晶矽的
受限態的近似及差異，在修改描述非晶矽似受體態的式子中特徵能量值使
其能合乎微晶矽特性後，建立了微晶矽薄膜電晶體的電腦模擬模型．在這
個微晶矽薄膜電晶體模擬模型中，微晶矽的能階大小是主要的參數．假設
微晶矽電子移動率和能階的變化有一定的關係．又考慮因為所有由電場所
引發而生成的載子中，只有小部分自由的載子可以自由傳導，所以在這個
微晶矽薄膜電晶體電流電壓特性模型中還引用了場效移動率的觀念．
由不同文獻所查得兩組實驗室之實驗數據，與我們以電腦模擬計算所得到
結果相當吻合．也就是說，我們所建立的微晶矽薄膜電晶體電流電壓特性
電腦模擬模型，不僅簡單而且具有通用性，在從非晶矽到微晶矽的範圍內
皆能夠適用．

A numerical simulation to predict and analyze the
characteristics of microcrystalline silicon thin-film
transistors have been proposed. Based on the gap-state model for
amorphous silicon TFTs presented earlier, the model was
presented by considering the energy gap instead of grain size as
a parameter of the degree of crtstallization of microcrystalline
silicon. The microcrystalline silicon acceptor-like state
characteristic energies are modified as the energy gap changes.
The band mobility of microcrystalline silicon is assumed to be a
function of the energy gap, and the concept of field-effect
mobility is adopted. The experimental data on microcrystalline
hydrogenated silicon TFT''s characteristics from Hsu''s work and
Liang''s work were adopted, while this theoretical model is
proposed to fit the Hsu''s experimental data and Liang''s
experimental data. Results show that our proposed model conforms
fairly well with the experimental data. This general and simple
TFT''s characteristics simulation model can be used in a wide
range from amorphous silicon to microcrystalline silicon.

COVER
ACKNOWLEDGMENTS
ABSTRACT
CONTENTS
FIGURE CAPTIONS
LIST OF SYMBOLS
CHAPTER ONE INTRODUCTION
1.1 Microcrystalline Silicon
1.2 Microcrystalline Silicon TFT
1.3 Numerical Simulation for Microcrystalline Silicon TFT
1.4 Hydrogenated Silicon
CHAPTER TWO THEORETICAL ANALYSIS
2.1 Amorphous, Polycrystallite and Microcrystallite
2.1.1 Difference among Amorphous, Microcrystallite and Polycrystallite
2.1.2 Band Structure of Amorphous and Microcrystallite
2.1.3 Modeling for Amorphous and Microcrystalline Silicon TFT
2.2 Important Parameters from Experimental Data
2.2.1 Parameters in Hsu''s Work
2.2.2 Parameters in Liang''s Work
2.3 The Density of Acceptor-Like States
2.3.1 Acceptor-Like States and Donor-Like States
2.3.2 The Density of Acceptor-Like States in the Upper Gap of a-Si:H
2.3.3 The Density of Acceptor-Like States in the Upper Gap of uc-Si:H
2.4 The Localized States and Free Electron Charge
2.4.1 Poisson''s Equation and Space-Charge in TFT Channel
2.4.2 Concentration of the Localized States and Free Electron Charge
2.5 The Free Electron Charge
2.6 The Current-Voltage Characteristics
2.6.1 TFT''s Drain Current
2.6.2 The Mobility of Microcrystalline Silicon
2.6.3 The Conductivity Current
2.7 Temperature
CHAPTER THREE RESULTS AND DISCUSSION
3.1 Microcrystalline Silicon Energy Gap
3.2 Programming
3.3 Concentration of the Localized States and Free Electron Charge
3.4 Threshold Characteristics
3.4.1 Band Bending
3.4.2 Free Electron Charge and Band Bending
3.4.3 Threshold Voltage
3.4.4 Leakage Current
3.5 uc-Si:H TFT''s Current-Voltage Characteristics
3.6 Field-Effect Mobility
3.7 Kink Effect
CHAPTER FOUR CONCLUSIONS
REFERENCES
FIGURES