Transport properties of single-crystal tetracene field-effect transistors with silicon dioxide gate dielectric

Single-crystal organic field-effect transistors (SX-OFETs) with channel lengths of 1 and 100 mum have been fabricated by adhering thin crystals of tetracene to freshly ashed SiO2 substrates containing countersunk gold contacts. The intrinsic transport properties of the tetracene single crystals, corrected for potential contact effects by using a standard four-probe configuration, have been measured from room temperature down to 4.2 K. These OFETs exhibit mobilities as high as 0.1 cm(2) V(-1)s(-1), subthreshold swings of <500 mV/decade, and I-on/I-off ratios in excess of 10(9). The larger devices (L=100 mum,W=1000 mum) show thermally activated mobilities over the temperature range 200 K<T<300 K, but thermally induced cracks in the crystal prevent this analysis from being extended to lower temperatures. The smaller devices have a greater probability of surviving to low temperatures without a crack permeating the active channel, and representative devices have been investigated over the full range 4.2 K<T<300 K. The transport mechanism in these smaller devices can be varied from thermally activated to nearly temperature invariant by the application of drain fields >10(5) V/cm. (C) 2004 American Institute of Physics.