title: Voltage-Controlled Ring Oscillators Based on Inkjet Printed Carbon Nanotubes and Zinc Tin Oxide.
abstract: A voltage-controlled ring oscillator is implemented with double-gate complementary transistors where both the n- and p-channel semiconductors are deposited by inkjet printing. Top gates added to transistors in conventional ring oscillator circuits control not only threshold voltages of the constituent transistors but also the oscillation frequencies of the ring oscillators. The oscillation frequency increases or decreases linearly with applied top gate potential. The field-effect transistor materials system that yields such linear behavior has not been previously reported. In this work, we demonstrate details of a material system (gate insulator, p- and n-channel semiconductors) that results in very linear frequency changes with control gate potential. Our use of a double layer top dielectric consisting of a combination of solution processed P(VDF-TrFE) and Al2O3 deposited by atomic layer deposition leads to low operating voltages and near-optimal device characteristics from a circuit standpoint. Such functional blocks will enable the realization of printed voltage-controlled oscillator-based analog-to-digital converters.
authors.affiliation: †Microelectronics Research Center, The University of Texas at Austin, Austin, Texas 78758, United States.|‡Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78712, United States.
authors.forename: Bongjun
authors.initials: B
authors.lastname: Kim
authors.affiliation: ‡Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78712, United States.
authors.forename: Jaeyoung
authors.initials: J
authors.lastname: Park
authors.affiliation: §Department of Materials Science and Engineering and Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States.
authors.forename: Michael L
authors.initials: ML
authors.lastname: Geier
authors.affiliation: §Department of Materials Science and Engineering and Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States.
authors.forename: Mark C
authors.initials: MC
authors.lastname: Hersam
authors.affiliation: †Microelectronics Research Center, The University of Texas at Austin, Austin, Texas 78758, United States.|‡Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78712, United States.
authors.forename: Ananth
authors.initials: A
authors.lastname: Dodabalapur
keywords: carbon nanotube; double-gate; printed electronics; thin-film transistor; threshold voltage; voltage-controlled oscillator; zinc tin oxide