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Kevin Wang Nanofabrication Seminar 2008/4/27. Carbon Nanotubes as Injection Electrodes for TFTs. Concept. Aguirre, C.M., Martel, R. et al. Engineering Physics, EP Montréal Chemistry, U. of Montréal Backgated. Thin Film. Pentacene Island. Fabrication – Island. Double-wall nanotubes
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Kevin Wang Nanofabrication Seminar 2008/4/27 Carbon Nanotubes as Injection Electrodes for TFTs
Concept • Aguirre, C.M., Martel, R. et al. • Engineering Physics, EP Montréal • Chemistry, U. of Montréal • Backgated • Thin Film • Pentacene Island
Fabrication – Island • Double-wall nanotubes • Form gaps - electrical breakdown • Contacts – optical lithography • Ti and Pd by e-beam evaporation • Anneal (vacuum) 550°C, 1h • Post-Breakdown
Fabrication – Island (cont.) • Spin-coat precursor • 2 mg/mL chloroform solution • 13,6-N-sulfinylacetamido- pentacene • Converts to pentacene (170-200°C) • Asymmetric CNT – Pd
Fabrication – TFT • SWNTs (10 nanotubes/μm2) • Ti contacts, optical • Lithography, liftoff • Sonicate free nanotubes • Anneal (vacuum) 550°C, 1h • Pentacene (50nm) • Vacuum sublimation (0.2nm/s)
Fabrication – TFT (cont.) • W/L = 200μm/20μm • Au or Ti, 30 nm thick
Performance – Island • 40 nm gap device • Ion/Ioff = 100 • Ion = 2nA (Vds = 8V) • Superlinear IV • Poor gate control • tox = 20 nm • Subthreshold Swing • 1.3V/dec
Asymmetric CNT-Pd • Injection from CNT side • 21x more current • CNT good emitter, poor collector?
Performance - TFT • CNT array – ideal linear behavior • Au, Ti – nonlinear, large contact barriers • Barrier at CNT lowered by • E-field enhancement • Molecular energy shift
Conclusion • Carbon nanotubesenhance transistor current • Effective barrier lowering at CNT-Pentacene interface
Additional • Ti contacts