Surface treatment of Parylene-C gate dielectric for highly stable organic field-effect transistors

Abstract

Poly(chloro-p-xylene) or Parylene-C is used as a polymer gate dielectric in organic field-effect transistors (OFETs). Although pristine Parylene-C possesses good physical and chemical properties, such as high dielectric strength, uniform thickness, pin-free surface morphology, and mechanical flexibility, its hydrophobic and rough surface can degrade the crystalline growth of semiconductor molecules and increase interface trap density. Herein, we investigated the surface treatment of Parylene-C with several organic and polymer materials, including methacryloxypropyltrimethoxysilane, hexamethyldisilazane, and dimethylchlorosilane-terminated polystyrene. This allowed modulation of surface hydrophobicity and roughness, thereby affecting the crystal morphology of the semiconductor layer growing on the gate dielectric surface, as well as the device performance and stability under gate-bias stress of the corresponding OFETs.