Aerosol jet printed, low voltage, electrolyte gated carbon nanotube ring oscillators with sub-5 μs stage delays

Mingjing Ha, Jung Woo T Seo, Pradyumna L. Prabhumirashi, Wei Zhang, Michael L. Geier, Michael J. Renn, Chris H. Kim, Mark C. Hersam, C. Daniel Frisbie

Research output: Contribution to journalArticlepeer-review

162 Scopus citations

Abstract

A central challenge for printed electronics is to achieve high operating frequencies (short transistor switching times) at low supply biases compatible with thin film batteries. In this report, we demonstrate partially printed five-stage ring oscillators with >20 kHz operating frequencies and stage delays <5 μs at supply voltages below 3 V. The fastest ring oscillator achieved 1.2 μs delay time at 2 V supply. The inverter stages in these ring oscillators were based on ambipolar thin film transistors (TFTs) employing semiconducting, single-walled carbon nanotube (CNT) networks and a high capacitance (∼1 μF/cm2) ion gel electrolyte as the gate dielectric. All materials except the source and drain electrodes were aerosol jet printed. The TFTs exhibited high electron and hole mobilities (∼20 cm2/(V s)) and ON/OFF current ratios (up to 105). Inverter switching times t were systematically characterized as a function of transistor channel length and ionic conductivity of the gel dielectric, demonstrating that both the semiconductor and the ion gel play a role in switching speed. Quantitative scaling analysis suggests that with suitable optimization low voltage, printed ion gel gated CNT inverters could operate at frequencies on the order of 1 MHz.

Original languageEnglish (US)
Pages (from-to)954-960
Number of pages7
JournalNano letters
Volume13
Issue number3
DOIs
StatePublished - Mar 13 2013

Keywords

  • Printed electronics
  • carbon nanotubes
  • delay time
  • ion conductivity
  • ion gel
  • ring oscillator

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