EFFECTS OF SURFACE-MODIFIED GATE INSULATOR ON THE ELECTRICAL CHARACTERISTICS OF ORGANIC THIN-FILM TRANSISTORS

The performance of organic thin film transistors (OTFTs) strongly depends on the surface states of the gate insulator. Top-contact (TC) OTFTs with modified gate insulator were demonstrated in this paper. The modified gate insulator layers consisted of SiO 2 as the gate insulator and OTS (octadecyltrichlorosilane) or PMMA (Poly (methyl methacylate)) as the modified layer. The devices with the modified layer had field-effect mobility larger than 10-3 cm 2/ Vs , which was twice that of the untreated OTFT. The on/off current ratio was increased one order of magnitude and reached more than 104. The leakage current was decreased from 10-9 A to 10-10 A. The results demonstrate that using modified gate insulators can obviously improve the performance of the OTFTs.