Contact Resistance Effects in Ni Drain-Source P3HT/PVA OFETs

Ni bottom contacts and Al top gate organic field effect transistors of Poly 3-hexylthiophene and cross-linked Poly Vinyl Alcohol with different channel lengths (5 μm, 10 μm, 20 μm and 40 μm) were made on glass substrates, using standard photolithography and oxygen plasma etching. The transistors presented good charge mobility, high ION/IOFF and excellent environmental and temporal stability. The Shockley model and the Transmission Line Method (TLM) were applied to characterize the transistors. Mobility was extracted by both methods, and the differences were discussed. The shorter the channel length and the higher the conductivity of the semiconductor, the greater the impact of the contact resistance. In such cases, the use of TLM for parameter extraction becomes essential.