Effect of UV irradiation on threshold voltage and subthreshold slope in pentacene TFT

Abstract

We report the influence of UV irradiation on the electrical properties of pentacene thin-film transistors (TFTs) with SiO2 gate insulator. The threshold voltage (V-th) shifted from - 9.0 to - 5.1 V and subthreshold slope reduced from 3.6 to 1.1 V/dec by the treatment before pentacene deposition. The UV treatment reduced the surface energy by removing the hydroxyl groups at the SiO2 surface. Thus, molecular packing of pentacene on the UV-treated SiO2 was improved, lowering the |V-th| value via the reduction of trap densities in the channel region. The decrease in interface state density reduced the subthreshold slope. (C) 2007 The Electrochemical Society.