High-mobility pentacene organic thin-film transistors achieved by reducing remote phonon scattering and surface-roughness scattering

摘要

Pentacene organic thin-film transistors (OTFTs) with very high carrier mobility have been achieved on both rigid and flexible substrates by using high-k gate dielectric and metal gate. The high-k gate dielectric with suitable thickness can reduce the surface-roughness scattering, while the metal gate can suppress the remote phonon scattering. As a result, based on NbLaO gate dielectric, OTFTs with high carrier mobility of 10.6 cm(2) V-1 s(-1) (7.99 cm(2) V-1 s(-1)) with the capacitance per unit area measured at frequency of 1 kHz and small threshold voltage of -0.92 V (-0.74 V) fabricated on Pd-coated Si substrate (Pd-coated vacuum tape) are realized, though they have rougher dielectric surface and smaller pentacene grains than their counterparts fabricated on n-Si substrate. Moreover, with the addition of 13-nm SiO2 interlayer between the NbLaO gate dielectric and metal gate electrode, the carrier mobility decreases by 71% and 65% for the OTFTs on Si and V.T. substrates, respectively, highlighting the importance of the RPS.