Nanochannel effect in polymer nanowire transistor with highly aligned polymer chains

Abstract

We established a process to develop well-defined polymer nanowire transistors made of liquid-crystalline semiconducting poly(9,9-dioctylfluorene-alt-bithiophene) (F8T2). Nano-scaled channels have been fabricated in gate insulator layers of SiO2 using a lithography technique. The nanochannels offer templates for forming polymer nanowires in which polymer chains are uniaxially aligned along the nanochannels through a nano-confinement effect. In addition, this process prevents the occurrence of serious damage during the inevitable etching process that is used to separate the nanowires from each other. We examined the electrical properties and polymeric chain alignment of F8T2 nanowires. Nanowire transistors exhibited carrier mobilities of 3.5 and 2.8 × 10−3 cm2/Vs for 54 and 130 nm wide nanowires, respectively. The carrier mobilities were about three times larger than that of a thin film transistor. Polarized UV-vis absorption analysis clarified that the improved carrier mobility can be attributed to the enhanced polymer chain alignment in the nanochannels. This approach has great potential as regards improving device performance, downsizing, and the large-scale integration of nanowire transistors with various kinds of device configurations.