title: All-amorphous-oxide transparent, flexible thin-film transistors. Efficacy of bilayer gate dielectrics.
abstract: Optically transparent and mechanically flexible thin-film transistors (TF-TFTs) composed exclusively of amorphous metal oxide films are fabricated on plastic substrates by combining an amorphous Ta(2)O(5)/SiO(x) bilayer transparent oxide insulator (TOI) gate dielectric with an amorphous zinc-indium-tin oxide (a-ZITO) transparent oxide semiconductor (TOS) channel and a-ZITO transparent oxide conductor (TOC) electrodes. The bilayer gate dielectric is fabricated by the post-cross-linking of vapor-deposited hexachlorodisiloxane-derived films to form thin SiO(x) layers (v-SiO(x)) on amorphous Ta(2)O(5) (a-Ta(2)O(5)) films grown by ion-assisted deposition at room temperature. The a-Ta(2)O(5)/v-SiO(x) bilayer TOI dielectric integrates the large capacitance of the high dielectric constant a-Ta(2)O(5) layer with the excellent dielectric/semiconductor interfacial compatibility of the v-SiO(x) layer in a-ZITO TOS-based TF-TFTs. These all-amorphous-oxide TF-TFTs, having a channel length and width of 100 and 2000 microm, respectively, perform far better than a-Ta(2)O(5)-only devices and exhibit saturation-regime field-effect mobilities of approximately 20 cm(2)/V x s, on-currents >10(-4) A, and current on-off ratios >10(5). These TFTs operate at low voltages (approximately 4.0 V) and exhibit good visible-region optical transparency and excellent mechanical flexibility.
authors.affiliation: Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113, USA.
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.forename: D Bruce
authors.initials: DB
authors.lastname: Buchholz
authors.forename: Jonathan W
authors.initials: JW
authors.lastname: Hennek
authors.forename: Robert P H
authors.initials: RP
authors.lastname: Chang
authors.forename: Antonio
authors.initials: A
authors.lastname: Facchetti
authors.forename: Tobin J
authors.initials: TJ
authors.lastname: Marks
mesh_terms: D004566:Electrodes; D007204:Indium / Q000737:chemistry; D008567:Membranes, Artificial; D010087:Oxides / Q000737:chemistry*; D010316:Particle Size; D012666:Semiconductors; D014001:Tin / Q000737:chemistry; D014173:Transistors, Electronic; D015032:Zinc / Q000737:chemistry
chemical_list: D008567:Membranes, Artificial; D010087:Oxides; D007204:Indium; D014001:Tin; D015032:Zinc