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 μ m have been fabricated by adhering thin crystals of tetracene to freshly ashed SiO 2 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 μ m , W = 1000 μ m ) 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 .