ICML Hanyang University Polymeric Materials for Information & Communication Organic Thin Film Transistor Edited by Song Ho, Kim

ICML Hanyang University Polymeric Materials for Information & Communication 1.What is the OTFT? 2.Structure of OTFT 3.Application of OTFT 4.Mechanism Operation 5. Pentacene TFT - Proposed Research - Fabrication of Pentacene TFT Characteristics & Analysis 6. OTFT Materials Contents

ICML Hanyang University Polymeric Materials for Information & Communication First Organic Transistor Using organic molecules (Polymers) rather than silicon for their active material. Semiconductor Advantages –Less Complex & Lower-cost Fabrication Solution Processing  Photolithographic patterning lower temperature manufacturing (60-120° C) Print-able Organic Transistors –Mechanical flexibility compatibility with plastic substances: foldable & light weight –Strong Optical Absorption and Efficient Emission What is the OTFT(organic thin-film transistor)?

ICML Hanyang University Polymeric Materials for Information & Communication Structure of OTFT (1)

ICML Hanyang University Polymeric Materials for Information & Communication Structure of OTFT (2) Various Structures of Organic Thin-Film Transistor Bottom-Contact Top-Contact Top-Gate Bottom-Gate Source Drain Dielectric Semiconductor Gate/Substrate

ICML Hanyang University Polymeric Materials for Information & Communication Very Similar to MOSFETs 3-Terminal Device –Voltage Controled Switch Structure of OTFT (3) Differences –Carrier Transport Discrete Energy Levels Hopping –Organic Active Layer –Depletion Devices

ICML Hanyang University Polymeric Materials for Information & Communication Organic Thin Film Transistor OLED Device Liquid Crystal Device E-ink Antenna Materials Integration Technology OLED Display Plastic TFT LCD E-paper, E-book Contactless Smart Card Wearable Computer Application of Organic TFT (1)

ICML Hanyang University Polymeric Materials for Information & Communication Flexible OLED Flexible LCD Organic Memory Image Sensor Bio Sensor Organic Laser Smart Card RFID Tag E-paper OTFT IC Technology Optical Technology Bio Technology Apparel Technology Sensor Technology Memory device Technology LCD Technology OLED Technology E-Paper Technology Electrical Fabric Application of Organic TFT (2)

ICML Hanyang University Polymeric Materials for Information & Communication _ _ gate gate dielectric pentacene sourcedrain glass substrate bias on gate hole accumulation in pentacene negative hole flows to drain positive depletion Mechanism of Operation

ICML Hanyang University Polymeric Materials for Information & Communication substrate - corning 7059 glass gate metal - Nickel gate dielectric - SiO 2 source/drain metal - Palladium All deposition was performed by Ion beam sputtering Penn. state Univ. Pentacene TFT

ICML Hanyang University Polymeric Materials for Information & Communication 1. Fabricate Pentacene TFT - gate insulating layer with high dielectric constant - reproducible patterning of pentacene film - source/drain metal with large work function - arrays of pentacene TFT 2. Measurement & Analysis - V g - I d curve - mobility, threshold voltage, subthreshold slope 3. Evaluation Proposed Research

ICML Hanyang University Polymeric Materials for Information & Communication drain pentacene active layer substrate - glass (Corning 7059) gate metal - Al, Ni, Cr gate dielectric - SiO 2, V 2 O 5, Al 2 O 3 source/drain metal - Au active layer - pentacene passivation layer substrate gate source gate dielectric passivation layer drain Schematic Figure of Pentacene TFT

ICML Hanyang University Polymeric Materials for Information & Communication Interfacial effect of metal/gate dielectric - contact resistance, diffusion, dielectric properties Adhesion of material - film lifting, process unstableness Making smooth film - the small surface roughness leads to molecular ordering Photolithographic condition for pentacene patterning - thickness of resist, expose time, develop time - resist/pentacene interface effect Process Factors

ICML Hanyang University Polymeric Materials for Information & Communication Gate sputter, evaporation wet etching Gate sputter, evaporation wet etching Gate dielectric sputter dry etching (RIE) Gate dielectric sputter dry etching (RIE) Source/drain sputter, evaporation wet etching, lift-off Source/drain sputter, evaporation wet etching, lift-off Pentacene ICBD, evaporation wet & dry etching Pentacene ICBD, evaporation wet & dry etching Passivation CVD dry etching (RIE) Passivation CVD dry etching (RIE) Fabrication Flow Chart

ICML Hanyang University Polymeric Materials for Information & Communication Requirement fabricated at low temperature ( < 300°C) smooth surface roughness have a high capacitance with low leakage current good phase stability reproducibility SiO 2, V 2 O 5, Al 2 O 3 Gate Dielectric Layer

ICML Hanyang University Polymeric Materials for Information & Communication C-V I-V AFM Electrical characteristics Electrical characteristics Roughness Interfacial effect Interfacial effect RBS I-V Au deposition on gate dielectric and annealing Au deposition on gate dielectric and annealing Deposition by Reactive sputtering Analysis of Gate Dielectric Layer

ICML Hanyang University Polymeric Materials for Information & Communication x x x x x10 -6 R.T 200µµ 2hr 200µµ 3hr 300µµ 400µµ SiO 2 Capacitance ( F/cm 2 ) Voltage (V) C-V Analysis of V2O5 Dielectric Material

ICML Hanyang University Polymeric Materials for Information & Communication Evaporation ICBD (Ion Cluster Beam Deposition) expected to evaluate pentacene properties Deposition technique Simple structure estimate pentacene properties Deposition of Pentacene Film

ICML Hanyang University Polymeric Materials for Information & Communication Photolithographical method - using photosensitized PVA as negative photoresist - UV expose & develop in water - etching unwanted pentacene layer in oxygen plasma - baking to remove water in pentacene layer dielectric layer pentacene photosensitized PVA Patterning of Pentacene Film

ICML Hanyang University Polymeric Materials for Information & Communication Field effect mobility(  fe ) and the threshold voltage(V th ) were obtained in the saturation region using the relation Positive threshold voltage arise from an initial accumulation layer at the pentacene/dielectric interface - positive gate voltage is required to turn the device fully-off Large on/off current ratio can be obtained with small gate voltage swing Operation Characteristics

ICML Hanyang University Polymeric Materials for Information & Communication substrate gate pentacene active layer source gate dielectric drain pentacene layer is normally conducting no overlap gate-source, gate-drain large drain current to flow at zero gate bias devices are turned off by applying positive gate bias transistor operating in depletion mode 3 mask steps no overlap gate-source, gate-drain Different Structure of Pentacene TFT

ICML Hanyang University Polymeric Materials for Information & Communication Number Name 133Pentacene Benzo[b]naphthacene 2,3:6,7-Dibenzanthracene beta,beta'-Dibenzanthracene 2,3,6,7-Dibenzoanthracene lin-Dinaphthanthracene lin-Naphthanthrene CAS: M W:278 L / B:2.226 Width:7.447Length:16.577Thickness:3.885 Structure of Pentacene

ICML Hanyang University Polymeric Materials for Information & Communication Organic Semi-Conductors of Processing Type

ICML Hanyang University Polymeric Materials for Information & Communication p-Type Materials of OTFT

ICML Hanyang University Polymeric Materials for Information & Communication Structure and mobility of fused aromatic Compounds p-Type Materials

ICML Hanyang University Polymeric Materials for Information & Communication Oligo-thiophenes and Oligo-phenylenes p-Type Materials

ICML Hanyang University Polymeric Materials for Information & Communication Thiophenylenes and their mobilities p-Type Materials

ICML Hanyang University Polymeric Materials for Information & Communication Polythiophene materials for FET Conjugated polymers for FET p-Type Materials

ICML Hanyang University Polymeric Materials for Information & Communication Hall mobility change of Poly(2-alkylthiophene)s by arrangement and stereo chemistry Hall Mobility Change of Polythiophenes

ICML Hanyang University Polymeric Materials for Information & Communication n-Type Materials of OTFT

ICML Hanyang University Polymeric Materials for Information & Communication Electron Mobilities of n-Type Materials

ICML Hanyang University Polymeric Materials for Information & Communication Tetracarboxylic anhydrides Quinodimethane compounds Phthalocyanines n-Type Materials

ICML Hanyang University Polymeric Materials for Information & Communication Fluorinated n-type materials n-Type Materials

ICML Hanyang University Polymeric Materials for Information & Communication Physical Properties of Organic Dielectric

ICML Hanyang University Polymeric Materials for Information & Communication Trends of OTFT Materials(Domestic)

ICML Hanyang University Polymeric Materials for Information & Communication Trends of OTFT Materials(Abroad)

ICML Hanyang University Polymeric Materials for Information & Communication Low conductivity and low carrier mobility of Organic semi-conductor Structure of General FET Low Current and low operating speed Improvement of physical properties Searching of New materials Improvement of Device Structure New mechanism High purity crystallinity Phase Transition FET SIT Problem and Solution of OTFT

ICML Hanyang University Polymeric Materials for Information & Communication Reference 1) 고분자 과학과 기술 제 17 권 1 호 2006 년 2 월 ‘ 유기반도체 재료 ’ 하승규, 권오식 2) 고분자 과학과 기술 제 14 권 5 호 2003 년 10 월 ‘ 유기트랜지스터 재료 연구개발 동향 ’ 권순기, 김윤희, 김형선, 안준환 3) 고분자 과학과 기술 제 15 권 6 호 2004 년 12 월 ‘ 고분자박막트랜지스터 개발동향 ’ 김보성, 이용욱, 홍문표, 정규하 4) 화학세계 04/06 50 ‘ 단분자 OLED 재료 및 OTFT 재료의 개발동향 ’ 권순기 3) 고분자 과학과 기술 제 14 권 1 호 2003 년 2 월 ‘ 유기 ’ 하승규, 권오식 5) University of the South Sewanee, Tennessee September 2002, Eugene Donev ‘Designing and Implementing Organic Thin-Film Transistors (OTFTs)’ 6) Adv. Mater. 2000, 12, No. 7 p.481, Groenendaal,* Friedrich Jonas, Dieter Freitag, Harald Pielartzik, and John R. Reynolds ‘Poly(3,4-ethylenedioxythiophene) and Its Derivatives: Past, Present, and Future’

ICML Hanyang University Polymeric Materials for Information & Communication Reference 7) Ali Ali Afzali Afzali, Christos Christos D. D. Dimitrakopoulos Dimitrakopoulos IBM Research Division T. J. Watson Research Center T. J. Watson Research Center Yorktown Heights, NY ‘Synthesis and Application of Pentacene Precursor in OTFT’ 8) Chang Feng Yu,Ching Fu Hsu, Yao Peng Chen, and Yu Hua Ma Department of Information and Communication Engineering Chaoyang University of Technology ‘Dependence of field-effect mobility on the gate field for Pentancene OTFTs’ 9) ~shlee/OTFT.htm 10) ce/lamp/research-4.html 11)