Regensburg 2004 – scientific programme

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SYOH: Organic and Hybrid Systems for Future Electronics

SYOH 5: Poster

SYOH 5.62: Poster

Thursday, March 11, 2004, 18:00–21:00, B

Downscaling of thiophene based organic field-effect transistors to the nanometer regime — •M. Leufgen¹, U. Bass¹, T. Borzenko¹, G. Schmidt¹, J. Geurts¹, T. Muck², and V. Wagner² — ¹Physikalisches Institut der Universität Würzburg, EP III, Am Hubland, D-97074 Würzburg — ²International University Bremen, School of Engineering and Science, Campus Ring 8, D-28759 Bremen

For future electronics high-performing organic field-effect transistors (OFETs) are required. Downscaling to channel lengths L in the nanometer regime means higher accessible frequency, integration and current of transistors. To vary L from 2 µm down to 50 nm, we use an assembly of n-type silicon wafer as common gate with thermally grown oxide as insulator layer and Au/Ti source and drain interdigitated electrodes, defined by electron beam lithography. In order to keep good characteristics downscaling the channel requires a thinner insulator layer because of the ratio of horizontal and transversal electrical field in the device. The thickness of the SiO₂ investigated ranges from 200 nm down to 30 nm. The active material is the soluble hexyl substituted quaterthiophene (DH4T). For the 30 nm oxide layers our results show high mobility of about 2× 10⁻² cm²/Vs for a 200 nm channel DH4T-device with ratio W/L of 800. Moreover, the linear and saturation regime are proven and on/off-ratios for devices with L down to 200nm are as high as 10⁵. Below 200nm field-effect is still observed, but the transistor performance decreases.