Improved Performance of Pentacene Thin-Film Transistors with Al2O3 Gate Dielectric: Annealing Effect on the Surface Properties

Abstract

We have fabricated pentacene thin-film transistors (TFTs) with modified Al2O3 layers as gate dielectrics. The effects of thermal treatments on the E-beam-processed Al2O3 layers in the TFTs were investigated by using various analytical tools such as X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), atomic force microscope (AFM), and a contact angle method. From the results of the analyses, it was confirmed that the performance of thermally treated Al2O3 gate dielectrics is much better than that of non-treated ones. Finally, pentacene TFTs were fabricated with optimum conditions and improved electrical properties were obtained for low-voltage (below -3 V) TFTs as follows: a mobility of 0.9 cm(2) V-1 s(-1), a threshold voltage of -1.3 V, a sub-threshold slope of 0.12 V/decade, and an on/off current ratio of 2.2 x 10(5). (c) 2012 The Japan Society of Applied Physics