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Solution-Processed High-k Dielectrics for Organic/Inorganic Thin-Film Transistors and CMOS Circuit Applications
용액 공정 고유전상수 절연체를 이용한 유무기 박막트랜지스터 및 상보형 회로 응용에 대한 연구

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dc.contributor.advisor홍용택-
dc.contributor.author지선범-
dc.date.accessioned2017-07-13T07:08:43Z-
dc.date.available2017-07-13T07:08:43Z-
dc.date.issued2015-02-
dc.identifier.other000000026132-
dc.identifier.urihttps://hdl.handle.net/10371/119077-
dc.description학위논문 (박사)-- 서울대학교 대학원 : 전기·컴퓨터공학부, 2015. 2. 홍용택.-
dc.description.abstractZinc-oxide (ZnO)-based materials have been widely investigated as an active channel layer of thin-film transistors (TFTs) due to their high mobility and optically high transparency related with the wide band gap and application to solution-process. Many kinds of ZnO-based TFTs have been reported for backplanes of active matrix liquid crystal displays (AMLCDs) and active matrix organic light emitting diodes (AMOLEDs). However, even though ZnO-based materials can be fabricated by solution-based processes, which are expected to simple and low cost method, most devices have been fabricated by expensive vacuum processes such as pulsed laser deposition (PLD) and sputtering method. Recently, there are many efforts for reducing the operational voltage of TFTs using high capacitance dielectrics. By incorporating the high capacitance dielectrics, more charges can be accumulated at dielectric and semiconductor interfaces at the same bias condition, hence, TFTs and circuits can be operated under a low voltage condition. Additionally, low-power consumption and high electrical performance including a low subthreshold swing (S.S) can be achieved.
In this dissertation, oxide TFTs and high-k dielectrics fabricated by solution-process are studied for low voltage high-performance TFTs and all solution-processed organic/inorganic hybrid complementary metal-oxide-semiconductor (CMOS)-type circuit applications.
First, the solution-processed indium-gallium-zinc-oxide (IGZO) TFTs, composed of inkjet-printed active channel layer and Ag source/drain (S/D) electrodes, were demonstrated. Inkjet-printed IGZO TFTs exhibited the high mobility above 2 cm2/Vs at 400 oC annealing temperature. Optimizations of inkjet-printing and thermal annealing conditions were required to achieve high performance characteristics.
Second, high-k Al2O3 and ZrO2 gate dielectrics were fabricated by spin-coating method for improving the electrical performance and reducing the operating voltage of oxide and organic TFTs. High capacitance of gate dielectrics enabled oxide and organic TFTs to operate in low-voltage condition under the 5 V. In particular, Al2O3 dielectric exhibited the amorphous phase and better TFT electrical behaviors such as high mobility and steep S.S. than ZrO2 dielectrics in both organic and oxide TFTs. And all solution-processed high-performance low-voltage IGZO TFTs were demonstrated. Additionally, a metal-insulator-semiconductor-metal (MISM) capacitor measurement was proposed for accuracy estimation of parameters due to the possibility of the additional electric double layer (EDL) formation through the mobile ions migration.
Finally, an organic/inorganic hybrid structure approach was proposed to achieve CMOS-type inverters. Demonstrated organic/inorganic hybrid CMOS-type inverter structure showed the improved electrical performance compared to previous reported inverters composed of only p-type TFTs. The effect of high-k dielectric on the hybrid CMOS-type inverter was also investigated to enhance the inverter performance.
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dc.description.tableofcontentsAbstract i
Contents iv
List of Figures viii
List of Tables xiv
Chapter 1 Introduction 1
1.1 Oxide Semiconductor Thin-Film Transistors 1
1.2 Solution-Process, CMOS, and High-k Dielectrics 6
1.3 Organization of This Dissertation 13
Chapter 2 High-Performance Inkjet-Printed IGZO TFTs 17
2.1 Introduction 17
2.2 Experiments 20
2.2.1 Device Structure and Process Flow 20
2.2.2 Substrate Cleaning and Surface Treatment 22
2.2.3 Inkjet-Printing of IGZO Active Layer 23
2.2.4 Inkjet-Printing of Conductive Silver Ink 27
2.3 Results and Discussion 29
2.3.1 Characterization of IGZO Solution and Films 29
2.3.2 Effect of Annealing Temperature on Electrical Characteristics of IGZO TFTs 35
2.3.3 Effect of IGZO Pattern Size on TFT Characteristics 43
2.3.4 Effect of Ag S/D Electrodes on IGZO TFTs 47
2.4 Summary 52
Chapter 3 Solution-Processed High-k Dielectrics for High-Performance Low-Voltage TFTs 55
3.1 Introduction 55
3.2 Low-Voltage IGZO TFTs 59
3.2.1 Fabrication of High-k Dielectrics and TFTs 59
3.2.2 High-k Film and MIM Capacitor Characteristics 62
3.2.3 Low-Voltage IGZO TFTs Characteristics 68
3.2.4 All Solution-Processed Low-Voltage IGZO TFT 72
3.3 Dielectric Dispersion Behavior of Solution-Processed High-Performance Low-Voltage IGZO TFTs on High-k Al2O3 Dielectric 75
3.3.1 Experimental 75
3.3.2 Results and Discussion 78
3.4 Low-Voltage Organic TFTs 84
3.4.1 Experimental 84
3.4.2 Results and Discussion 86
3.5 Summary 100
Chapter 4 Solution-Processed Organic/Inorganic Hybrid CMOS-type Inverter 103
4.1 Introduction 103
4.2 Hybrid CMOS on SiO2 Dielectric 108
4.2.1 Structure and Fabrication Process 108
4.2.2 Electrical Characteristics 113
4.3 Low-Voltage Hybrid CMOS Inverter 118
4.3.1 Structure and Fabrication Process 118
4.3.2 Electrical Characteristics 121
4.4 Summary 126
Chapter 5 Conclusion 129
한글 초록 131
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dc.formatapplication/pdf-
dc.format.extent4007204 bytes-
dc.format.mediumapplication/pdf-
dc.language.isoen-
dc.publisher서울대학교 대학원-
dc.subjectthin-film transistors (TFTs)-
dc.subjectindium-gallium-zinc-oxide (IGZO)-
dc.subjectoxide semiconductor-
dc.subjecthigh-k dielectrics-
dc.subjectcomplementary metal-oxide-semiconductor (CMOS)-
dc.subjectinverter-
dc.subjectsolution-process-
dc.subjectinkjet-printing-
dc.subjectspin-coating-
dc.subjectpentacene-
dc.subjectorganic semiconductor-
dc.subject.ddc621-
dc.titleSolution-Processed High-k Dielectrics for Organic/Inorganic Thin-Film Transistors and CMOS Circuit Applications-
dc.title.alternative용액 공정 고유전상수 절연체를 이용한 유무기 박막트랜지스터 및 상보형 회로 응용에 대한 연구-
dc.typeThesis-
dc.contributor.AlternativeAuthorSeon-Beom Ji-
dc.description.degreeDoctor-
dc.citation.pagesxiv, 133-
dc.contributor.affiliation공과대학 전기·컴퓨터공학부-
dc.date.awarded2015-02-
Appears in Collections:
College of Engineering/Engineering Practice School (공과대학/대학원)Dept. of Electrical and Computer Engineering (전기·정보공학부)Theses (Ph.D. / Sc.D._전기·정보공학부)
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