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

摘要

P-channel pentacene field effect transistorswith a Si/SiO_2/pentacene/Au structure were fabricated, and were gamma-ray irradiated with a Co~(60) source. The changes of the drain current ID vs. source/drain voltage V_(SD) (ID - V_(SD)) characteristics were measured after every 200 Gy in silicon (Gy_(Si)) irradiations up to the total dose of 1200 Gy_(Si). The drain current ID continuously decreased to less than 10% of that before irradiation after 1200 Gy_(Si) irradiation. The threshold voltage V_(th) continuously decreased up to 800 Gy_(Si), started to saturate above 800 Gy_(Si), and recovered above 1000 Gy_(Si). The mobility μ continued to decrease up to 1200 Gy_(Si). Those behaviors were explained by accumulation of positive trapped charge within the gate insulator SiO_2 near the interface, continuous increase of interface traps near the interface between the SiO_2 and 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.