Effect of gate metal on polymer transistor with glass substrate

Abstract

Poly(3-hexylthiophene) (P3HT) field-effect transistors (FETs) are fabricated on glass substrates with SiO2 as a gate dielectric over the gate. Indium tin oxide (ITO), Al, and Cr are employed as gate metals. For spin-coated FET, the mobility increases from 10(-4)-10(-5) cm(2)/V s for ITO and Al gates to 10(-2) cm(2)/V s for Cr gate. After O-2 plasma treatment, the SiO2 roughness can be made as low as 0.7 nm. The mobility is further improved up to 0.3 cm(2)/V s by dip-coating P3HT. "Crossed rods" such as morphology can be observed in dip-coated FET with high mobility, indicating high degree of self-assembly facilitated by the flat SiO2 surface over Cr gate. (c) 2006 American Institute of Physics.