Browsing by Author "Tsai, Yun-Chu"

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Enhanced field-effect mobility in pentacene based organic thin-film transistors on polyacrylates
(2009-03-15)
Cheng, Jung-An
;
Chuang, Chiao-Shun
;
Chang, Ming-Nung
;
Tsai, Yun-Chu
;
Shieh, Han-Ping D.
We reported on organic thin-film transistors (OTFTs) with high dielectric constant polymer, poly(2,2,2-trifluoroethyl methacrylate) (PTFMA), as the gate dielectric. In top-contact OTFTs, the field-effect mobility was enhanced by applying a dielectric buffer layer poly(alpha-methylstyrene) to the bare PTFMA. After improving interfacial affinity within the active layer/dielectrics, deposited pentacene grain size and device performance were enhanced dramatically. The corresponding mobility, threshold voltage, and on/off current ratio were 0.70 cm(2) V(-1) s(-1), -10.5 V, and 5.4x10(5), respectively. The moderately improved interface also suppressed the hole-trapping effect, which led to less hysteresis and minimized threshold voltage shift.
Influences of Nitrogen Doping on the Electrical Characteristics of Indium-Zinc-Oxide Thin Film Transistors
(2016-12)
Han, Yanbing
;
Yan, Hai
;
Tsai, Yun-Chu
;
Li, Yan
;
Zhang, Qun
Thin film transistors (TFTs) with nitrogen doped amorphous indium-zinc-oxide (a-IZO:N) as the channel layer were prepared by rf magnetron sputtering with an argon, oxygen, and nitrogen gas mixture at room temperature. XRD measurements confirm the amorphous structure of a-IZO:N thin film and AFM verifies its uniformity. Transmittance curves show that nitrogen doping in a-IZO films can narrow the optical band gap and suppress oxygen vacancies, which is also proved by XPS. When the nitrogen flow rate is 4 SCCM, a-IZO TFTs possess optimized the characteristics, with saturation mobility 24.67 cm(2)V(-1)s(-1), subthreshold swing 0.41 V/decade, on/off ratio 1.7 x 10(9), and threshold voltage -14.46 V. Threshold voltages shift from -22.76 to -9.59 V as the nitrogen flow rate raises from 0 to 6.5 SCCM. The positive gate bias stability and negative bias illumination stability of a-IZO:N TFT are also improved with the nitrogen flow rate of 4 and 2.5 SCCM, respectively.