臺灣博碩士論文加值系統

旋塗式有機薄膜電晶體有利於大面積且低成本的元件製作,因為有機薄膜電晶體的效能跟半導體與介電層的介面有很大的關係,所以此篇論文的研究目標是藉由化性控制聚合物與介電層之間的介面,並呈現有機薄膜電晶體的改良特性.而因為二氧化矽的特性可被掌握且介面改質容易,在此我們選擇熱氧化方式的二氧化矽作為我們的介電層.使用六甲基二矽氮烷對二氧化矽絕緣層進行表面處理來製作高規則度聚(3-烷基�囮h)為材質之薄膜電晶體.經由六甲基二矽氮烷的自組裝層所處理的氧化層介面, P3HT薄膜電晶體將獲得明顯的改善.我們將使用常壓式電漿來實現介面處理.而常壓電漿系統是一種可以將製程溫度操控於120度以下,並可工作於大氣壓力下.在本文可以觀察這些表面處理過後的效應.處理過後的臨界電壓可被降至-10伏特以內,載子遷移率也提昇15倍以上而達到0.02-0.03 cm2/Vs.在本文中,使用常壓式電漿系統確實提供執行表面處理的技術以獲得低溫高效率的有機薄膜電晶體元件.

Organic thin film transistors made by Spin-Coating method with solution processable conjugated polymers have potentila advantages for fabricating low-cost, large area devices. Because OTFT performance depends strongly on the interface of semiconductor and dielectric layer. The purpose of this work is to show that improved characteristics of P3HT-based OTFT are obtained by controlling the chemistry of the dielectric/polymer interface. We chose to use thermal SiO2 as the dielectric because of its well-characterized properties and ease of chemical modification. The characteristics of thin-film transistor (TFT) fabricated with high regioregularity poly(3-hexylthiophene) (rr-P3HT). P3HT can be improved significantly by modify the surface of SiO2 with hexamethyldisilazane (HMDS) self-assembled monolayer. Before deposition of active layer, the surface modification can be carried out by means of atmospheric-pressure plasma technology (APPT). APPT is new process that can be operated in atomspheric and low temperature ambient. Processes of APPT are below 120°C and at atmospheric pressure. The effects of surface treatment of SiO2 on electric characteristics of OTFTs were investigated. After surface treatment, the field-effect transistor has a threshold voltage within -10V and a field-effect mobility of 0.02-0.03 cm2/Vs which is 15-fold improvement over the mobility on bare silicon oxide. This study suggests an interesting direction for preparation of high-performance OTFTs with high efficiency and low temperature of surface treatment process by APPT.

Contents

Chinese Abstract…………………………………………………………………….i
English Abstract…………………………………………………………………….iii
Acknowledgement…………………………………………………………………..v
Contents……………………………………………………………………………..vi
Table Captions……………………………………………………………………...vii
Figure Captions…………………………………………………………………….viii

Chapter 1 Introduction……………………………………………………………...1
1.1 General Background and Motivation…………………………..………. …...1
1.2 Thesis Organization…………………...……………………………………..3
Chapter 2 Experiment…………..………………………………….………………..6
2.1 Introduction of Poly(3-hexylthiophene)P3HT…..……………...……………6
2.1.1 The Molecular structure of P3HT…………………………………… 6
2.1.2 Conduction Mechanism………………………………………………7
2.2 Solution processed deposition……..………………………………………...7
2.2.1 Methods of OTFTs fabricates………………………………...……....8
2.2.2 The Motivation for Spin-Coat……………………………….……….9
2.2.3 Effect of Polymer Morphology and solvents………………………..10
2.3 Contact Resistance of P3HT OTFT...………………………………………11
2.4 Operation of Organic Thin Film Transistors………………………………..12
Chapter 3 Influence of APPT for OTFT………...…………………………...……22
3.1 Introduction of APPT……………………………………….………………22
3.1.1 Introduction of plasma………………………………………………22
3.1.2 Applications of APPT……………………………………………….23
3.1.3 Surface modification by plsama………………………………………23
3.2 Fabrication of OTFT..……………………………….………......………….26
3.3 Determination of Thershold voltage and Mobility…..……………………...27
3.4 Results and discussion…………………………………………...………….28
3.4.1 The influence of Spin speed for OTFT……………………………….28
3.4.2 The influence of APPT………………………………………………..29
3.4.3 Another methods of HMDS-treated SiO2...………………………......31
Chapter 4 Conclusions and Future work..………………………………………...61
4.1 Conclusions....................................................................................................61
4.2 Future work....................................................................................................62
4.2.1 An in-situ passivation layer for protecting the P3HT film...................62
4.2.2 A new method to deposit P3HT thin film.............................................62
4.2.3 Thermal stability of P3HT OTFT..........................................................63
4.2.4 New gate insulator materials for P3HT OTFT......................................63

Reference....................................................................................................................64

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