Origin Of The Ambipolar Operation Of A Pentacene Field-effect Transistor Fabricated On A Poly(vinyl Alcohol)-coated Ta_2o_5 Gate Dielectric With Au Source/drain Electrodes

摘要

Pentacene field-effect transistors (FETs) were fabricated on a poly(vinyl alcohol) (PVA)-coated Ta_2O_5 gate dielectric using Au source/drain electrodes. Their device characteristics were examined before and after annealing the FETs in a vacuum. Before annealing, the pentacene FET showed an ambipolar operation with hole mobility of 0.1 cm~2 V~(-1) s~(-1) and electron mobility of 0.005 cm~2 V~(-1) s~(-1). After annealing at 50 ℃, however, the p-type operation characteristics almost diminished and an enhanced n-type operation was observed. Na~+ ions in the PVA are supposed to change the character of the injection barrier at the Au/pentacene junction and enable the n-type operation.