Characteristics of Gamma–Ray Irradiated Pentacene Organic Thin Film Field Effect Transistors

Abstract

P-channel pentacene field effect transistorswith a Si/SiO2/pentacene/Au structure were fabricated, and were gamma-ray irradiated with a Co60source. The changes of the drain current IDvs. source/drain voltage VSD(ID- VSD) characteristics were measured after every 200 Gy in silicon (GySi) irradiations up to the total dose of 1200 GySi. The drain current IDcontinuously decreased to less than 10 % of that before irradiation after 1200 GySiirradiation. The threshold voltage Vthcontinuously decreased up to 800 GySi, started to saturate above 800 GySi,and recovered above1000 GySi. The mobility m continued to decrease up to 1200 GySi. Those behaviors were explained by accumulation of positive trapped charge within the gate insulator SiO2near the interface, continuous increase of interface traps near the interface between the SiO2and pentacene, and build up of electrons in the channel regions. These behaviors were discussed in comparisons with previously reported results on ultraviolet (UV) light irradiation experiments on similarly structured pentacene-based transistors.