Surface-treatment effects on organic thin-film transistors

We have fabricated organic thin-film transistors (OTFTs) using pentacene as an active layer with chemically modified SiO2 gate dielectrics. The effects of the surface treatment of SiO2 on the electric characteristics of OTFTs were investigated. The SiO2 gate dielectric surfaces were treated by normal wet-cleaning process, O-2-plasma treatment, hexamethyldisilazane (HMDS), and octadecyltrichlorosilane (OTS) treatment. After the surface treatments, the contact angle and surface free energy were measured in order to analyze the surface state changes. From the electrical measurements, typical I-V characteristics of TFTs were observed. The field effect mobility, mu, was calculated to be 0.29 cm(2) V-1 s(-1) for OTS-treated sample, while those of the HMDS, O-2-plasma treated, and wet-cleaned samples to be 0.16, 0.1, and 0.04 cm(2) V-1 s(-1), respectively. (C) 2004 Elsevier B.V. All rights reserved.