Effect of stacked dielectric with high dielectric constant and surface modification on current enhancement in pentacene thin-film transistors

• Published in: Current applied physics Vol. 13; no. 1; pp. 170 - 175
• Main Authors: Park, Chang Bum, Lee, Jong Duk
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.01.2013; 한국물리학회
• Subjects: crosslinking; Current enhancement; Devices; Dielectric constant; Dielectric properties; Dielectric strength; energy; High dielectric constant; Hybrid dielectric; hydrophobicity; Insulators; Organic transistor; Pentacene; Polymethyl methacrylates; polyvinyl alcohol; Polyvinyl alcohols; Semiconductor devices; silica; Surface modification; Thin films; 물리학; Organic transistor; Pentacene; Surface modification; Hybrid dielectric; Current enhancement; High dielectric constant
• ISSN: 1567-1739; 1878-1675
• DOI: 10.1016/j.cap.2012.07.004

The effect of a stacked dielectric has been studied on pentacene thin-film transistors (TFTs) with respect to the current enhancement, the crystalline polymorph, and the structural change of the film. Here we show that the performance improvement of the device is successfully achieved by the dielectric effects of the high dielectric constant and the surface modification in hybrid dielectric configuration. The systematic analysis on the device feature governed by the interfacial property was carried out for a hybrid structured insulator system using SiO2 and cross-linked (C-L) polyvinyl alcohol (PVA), including the surface modified layer of dilute polymethyl methacrylate (PMMA). Through thickness combinations of bilayer dielectrics with low-k SiO2 and high-k PVA, the device also exhibits noticeable enhancement of the current drivability up to the current level of 94 μA at a practical gate bias of −30 V. Moreover, we present the effect of a surface-modified layer with dilute PMMA. After the formation of ultra-thin PMMA layer in a bilayer insulator, the organic dielectric shows an effectively changed surface property into hydrophobicity even on a strong hydroxyl-rich dielectric surface, resulting in the distinct increase of structural order in the film due to the reduction of surface free energy. ► We identify the current enhancement feature resulting from both dielectric effects. ► A hybrid dielectric configuration is proposed using low-k SiO2 and high-k C-L PVA. ► Hydrophobic property is achieved even a strong hydroxyl-rich dielectric surface. ► Low-surface-energy results in the distinct increase of structural order of films.