Improvement of Short Channel Mobility and Operational Stability of Pentacene Bottom-Contact Transistors with a Sulfuric Acid and Hydrogen Peroxide Mixture (SPM) Treatment of Au Electrodes
We report a reduction in the contact resistance between pentacene and Au source/drain electrodes of organic field effect transistors (OFETs) with bottom-contact structure. By immersing the Au electrodes in a sulfuric acid and hydrogen peroxide mixture (SPM), the injection barrier between the Au electrodes and pentacene was lowered by approximately 0.2eV and the contact resistance significantly decreased. The fabricated bottom-contact OFETs revealed a field-effect mobility of more than 0.66cm{sup}2/Vs at a channel length ranging from 3 to 30μm, which is comparable to that of top-contact OFETs with a 50μm channel length. The transfer characteristics of the OFET with the SPM treatment were stable even after 44days storage in air under room illumination without any passivation. Moreover, the drain current reduction due to threshold voltage (Vth) shift under continuous application of gate voltage quickly recovered toward the original value with unloading of gate voltage.
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