K. Leedy

Publications (4)9.28 Total impact

• Article: Electro-optic polymer spatial light modulator based on a Fabry-Perot interferometer configuration.

  Charles Greenlee, J Luo, K Leedy, B Bayraktaroglu, R A Norwood, M Fallahi, A K-Y Jen, N Peyghambarian
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  ABSTRACT: A spatial light modulator (SLM) based on a Fabry-Perot interferometer configuration has been fabricated and tested. The Fabry-Perot spacer layer is a thin film of the SEO100 electro-optic polymer which serves as the nonlinear medium. Measurement results demonstrate the modulation of multiple pixels operating simultaneously at frequencies ranging from 300 kHz to 800 kHz which is significantly faster than SLMs based on liquid crystal and digital micromirror device technology. An average modulation contrast of 50% for all pixels is achieved with a drive voltage of 70 V(rms) at 100 kHz. Microwave speeds and CMOS compatibility are feasible with improved transmission line and cavity design.
  Optics Express 06/2011; 19(13):12750-8. · 3.59 Impact Factor
• Article: High-Frequency ZnO Thin-Film Transistors on Si Substrates

  B. Bayraktaroglu, K. Leedy, R. Neidhard
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  ABSTRACT: Record microwave frequency performance was achieved with nanocrystalline ZnO thin-film transistors fabricated on Si substrates. Devices with 1.2-mum gate lengths and Au-based gate metals had current and power gain cutoff frequencies of f_T = 2.45 GHz and f_max = 7.45 GHz, respectively. Same devices had drain-current on/off ratios of 5 times10¹⁰ exhibited no hysteresis effects and could be operated at a current density of 348 mA/mm. The microwave performances of devices with 1.2- and 2.1- mum gate lengths and 50- and 100-mum gate widths were compared.
  IEEE Electron Device Letters 10/2009; · 2.85 Impact Factor
• Article: Microwave ZnO Thin-Film Transistors

  B. Bayraktaroglu, K. Leedy, R. Neidhard
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  ABSTRACT: We have developed ZnO thin-film transistor design and fabrication techniques to demonstrate microwave frequency operation with 2-mum gate length devices produced on GaAs substrates. Using SiO₂ gate insulator and pulsed laser deposited ZnO active layers, a drain-current ON/OFF ratio of 10¹², a drain-current density of 400 mA/mm, a field-effect mobility of 110 cm²/V ldr s, and a subthreshold gate voltage swing of 109 m/dec were achieved. Devices with Ti-gate metal had current and power gain cutoff frequencies of 500 and 400 MHz, respectively.
  IEEE Electron Device Letters 10/2008; · 2.85 Impact Factor
• Conference Proceeding: High Frequency ZnO Thin Film Transistors

  B. Bayraktaroglu, K. Leedy, R. Neidhard
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  ABSTRACT: Thin film transistors (TFT) are the essential elements of flat panel display electronics. The current technology for this application based on amorphous or polycrystalline Si films has speed limitations due to low mobility of such films. As the demand for higher speed electronics increase with display size and complexity, alternative technologies are being developed based on heavy metal oxide compounds such as ZnO. The increased mobility offered by this technology together with its robustness to environmental conditions, make it a suitable candidate for future applications.
  Device Research Conference, 2008; 07/2008