Hybrid La 2 O 3 -cPVP Dielectric for Organic Thin Film Transistor Applications

Abstract

In this work, we have studied the electrical performance of cross-linked polyvinyl phenol (cPVP) modified lanthanum oxide (La 2 O 3 ) bilayer dielectric film in pentacene thin film transistors (TFT). A simple spin-coating and room temperature operated cross-linking reaction of the hydroxyl moieties of PVP and the nitrogen groups of PMF were carried out to form the cross-linked PVP. The deposition of a thin 30 nm cPVP layer over the La 2 O 3 layer provided a low leakage current (<10 −7 A cm −2 ), causing a reduction in the interface trap density. Besides, the modified surface properties of the La 2 O 3 layer were favorable for the growth of pentacene organic semiconductors. As a result, the current on-off ratio and the sub-threshold slope was improved from 10 4 and 1.0 V/decade to 10 5 and 0.67 V/decade. The La 2 O 3 ∕cPVP pentacene TFT operated at −10 V also exhibited improvement in the field-effect mobility to 0.71 cm 2 Vs −1 from 0.48 cm 2 Vs −1 for the single-layer La 2 O 3 (130 nm) device. Thus, our work demonstrates that the rare earth oxide La 2 O 3 with cPVP is an excellent dielectric system in the context of emerging transistors with hybrid polymer gate dielectrics.