Thesis Table of Contents
          
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   Abstract

          

   

    Thesis

 
 

Table of Contents

 
Acknowledgements..................................................................... (i)
List of Figures........................................................................... (vii)
List of Tables............................................................................. (xiv)
List of Symbols........................................................................... (xv)
Abstract................................................................................... (xxi)
List of Publications...................................................................... (xxix)
Chapter-1:
INTRODUCTION…………………………..………………....................…. (1–45)
1.1

Evolution of Thin–Film Transistor (TFT)..........................

4
1.2

Thin–Film Field–Effect Transistors.................................

5
1.2.1

Device Physics..........................................................

6
1.2.1.1

Conduction Phenomena...............................................

7
1.2.1.2

Poly–Silicon Film Properties..........................................

8
1.2.1.3

Electrical Characteristics of Poly–Si TFT....................... 

10
1.2.2

Advantages............................................................

13
1.2.2.1

Single Process Fabrication.........................................

13
1.2.2.2

Low Temperature Deposition......................................

13
1.2.2.3

Isolation.................................................................

13
1.2.2.4

Assembly................................................................

13
1.2.2.5

Substrates.............................................................

14
1.3

Fabrication of Thin–Film Transistors.............................

14
1.3.1

Different TFT Structures...........................................

14
1.3.2

Fabrication Techniques.............................................

15
1.3.3

Device performance and Feature Size..........................

17
1.3.4

Factors Affecting the Electrical Properties....................

18
1.4

Comparisons...........................................................

19
1.4.1

Comparison of Display Technology: CRT vs. AMLCD........

19
1.4.2

Comparison of a–Si and poly–Si TFTs...........................

19
1.4.3

Classification of Thin–Silicon Materials..........................

20
1.5

TFT Applications......................................................

21
1.5.1

Active–Matrix liquid Crystal Display (AMLCD).................

21
1.5.2

Electro–phoretic Display (EDP)....................................

23
1.5.3

Static–Random Access memory (SRAM)........................

26
1.5.4

Image Sensors........................................................

27
1.6

Future Trends.........................................................

29
1.6.1

Poly–Si TFTs on Plastics............................................

29
1.6.2

Poly–Si TFTs on Metal Foils........................................

30
1.6.3

Poly–Si TFTs on Paper (Organic TFT)...........................

31
1.7

Device Modeling.......................................................

32
1.7.1

Analytical Models.....................................................

34
1.7.2

Table Lookup Model..................................................

35
1.7.3

Empirical Model........................................................

35
1.8

Scope of Thesis.......................................................

36
1.9      References............................................................. 40
     
Chapter-2:
Quasi Two–Dimensional Modeling of TFT....................................... (47–83)
2.1

Introduction............................................................

49
2.2

Temperature Dependent Model...................................

50
2.2.1

Threshold Voltage....................................................

52
2.2.2

Drain Voltage Characteristics.....................................

60
2.2.2.1

Field Effect Mobility..................................................

61
2.2.2.2

Drain Current Characteristics......................................

64
2.2.2.2.1

Linear Region (E<Ec).................................................

64
2.2.2.2.2

Saturation Region (E>Ec)...........................................

65
2.2.3

Transconductance...................................................

68
2.2.4

Cut–off Frequency and Transit Time............................

74
2.3

Summary................................................................

80
2.4

References.............................................................

81
Chapter-3:
The Kink effect analysis in Post–Saturation Region......................... (85–106)
3.1

Introduction............................................................

87
3.2

Model Formulation....................................................

90
3.2.1

Channel Potential.....................................................

91
3.2.2

Kink Current............................................................

96
3.3

Summary..............................................................

103
3.4

References............................................................

105
Chapter-4:
Two–Dimensional Potential Distribution Analysis........................... (107–148)
4.1

Introduction..........................................................

109
4.2

Model Formulation..................................................

112
4.2.1

Potential Distribution Model......................................

112
4.2.2

Horizontal Electric Field at Si– SiO2 Interface................

129
4.2.3

Minimum Surface Channel Potential Position.................

132
4.2.4

Threshold Voltage..................................................

135
4.2.5

Sub–threshold Swing...............................................

139
4.2.6

Transfer Characteristics..........................................

142
4.2.6.1

Drain Current.........................................................

142
4.2.6.1.1

Linear Region.........................................................

142
4.2.6.1.2

Saturation Region...................................................

142
4.2.6.2

Transconductance and Cut–off Frequency..................

143
4.3

Summary..............................................................

145
4.4

References............................................................

146
Chapter-5:
Threshold Voltage Optimization................................................... (149–181)
5.1

Introduction..........................................................

151
5.2

Model Formulation..................................................

153
5.2.1

Potential Distribution Model......................................

154
5.2.1.1

Effect of Double Gate..............................................

161
5.2.1.2

Effect of Gate Dielectric and Work–Function................

163
5.2.2

Horizontal Electric Field at Si– SiO2 Interface................

164
5.2.3

Threshold Voltage...................................................

167
5.2.3.1

Impact of Double Gate.............................................

169
5.2.3.2

Impact of Device Parameters....................................

170
5.2.4

Drain Current.........................................................

172
5.3

Summary...............................................................

178
5.4

References............................................................

180
Chapter-6:
Improved Gate Transport Device: Multi–Material–Gate Analysis...... (183–215)
6.1

Introduction..........................................................

185
6.2

Model Formulation..................................................

189
6.2.1

Potential Distribution Model......................................

190
6.2.1.1

Effect of MMG Structures........................................

197
6.2.1.2

Effect of Work–Function and Gate–Junction Position Alteration..............................

199
6.2.2

Threshold Voltage..................................................

202
6.2.3

Drain Current and Channel Length Modulation..............

207
6.2.3.1

Linear Region.........................................................

207
6.2.3.2

Saturation Region...................................................

208
6.2.4

Transconductance..................................................

210
6.2.5

Summary..............................................................

211
6.2.6

References............................................................

213
Chapter-7:
Conclusion.................................................................................. (217–225)
7.1

Summary and Conclusion.........................................

219
7.2

Future Scope........................................................

225
Appendix: Green Function Solution........................................................... (227–237)
 
   

     

Abstract    Thesis