Papers by Keyword: Organic Thin-Film Transistor

Abstract: Dissolved Poly (methyl methacrylate) (PMMA) in Dimethylformamide solution was fabricated as thin films on different substrates, glass, poly (ethylene naphthalate) and Si wafer, using spin coating technique. The effect of different substrates on electrical performances of the PMMA films was investigated. For an acceptable organic thin-film transistor (OTFT) performance, uniform thickness with low defect density of the PMMA thin-films was required. A parallel plate capacitor structure was used to test electrical properties of the PMMA dielectric layers. Good dielectric properties were obtained on glass and PEN at film thicknesses of 95 nm. An optimal condition for the OTFT preparation was used to fabricate an OTFT with the PMMA dielectric layer on glass substrate. Measured results showed that the OTFT achieved a mobility of 0.16 cm²/V.s, a threshold voltage of -3.6 V, and on/off current ratio of 1×10⁵.

Abstract: We investigated the characteristics of pentacene thin films of different materials for gate insulators using atomic force microscope (AFM) and x-ray diffraction (XRD). The pentacene thin films are fabricated by evaporation on different polymer substrates. We used HMDS (Hexa Methyl Di Silazane), PVA (Poly Vinyl Alcohol) and PMMA (Poly Methyl Meth Acrylate) for the polymer substrates, on which pentacene is deposited at various substrate temperatures. The case of pentacene deposited on the PMMA has the largest grain size and least trap concentration. We also fabricated pentacene TFTs with the PMMA gate insulator. Pentacene TFTs with PMMA gate insulator, shows high field-effect mobility (ｕFET= 0.03 cm2/Vs) and large on/off current ratio (>105) and small threshold voltage (Vth= -6 V).

Abstract: We report on the fabrication of dual-gate pentacene organic thin-film transistors (OTFTs) using a plasma-enhanced atomic layer deposited (PEALD) 150 nm thick Al2O3 as a bottom gate dielectric and a 300 nm thick parylene or a PEALD 200 nm thick Al2O3 as both a top gate dielectric and a passivation layer. The threshold voltage (Vth) of OTFT with a 300 nm thick parylene as a top gate dielectric is changed from 4.7 V to 1.3 V and that with a PEALD 200 nm thick Al2O3 as a top gate dielectric is changed from 1.95 V to -9.8 V when the voltage bias of top gate electrode is changed from -10 V to 10 V. The change of Vth of OTFT with the dual-gate structure has been successfully understood by an analysis of electrostatic potential.