One-step micropatterning of highly-ordered semi-crystalline poly(vinylidene fluoride-co-trifluoroethylene) films by a selective shear and detachment process

Abstract

We present a one-step route for micropatterning a thin ferroelectric poly(vinylidene fluoride-co-trifluoroethylene) (PVDF-TrFE) film with both molecular and microstructural crystal control over a large area. The method is based on the static mechanical shearing and ;subsequent detachment of a film spin coated on pre-patterned Al which has been lithographically prepared on a SiO2 substrate under appropriate thermal conditions. Selective detachment of the film in contact with the SiO2 substrate gave rise to micropatterns of PVDF-TrFE film positioned only on the Al regions. Further, the PVDF-TrFE film showed 25-nm-thick crystalline lamellae aligned perpendicular to the shear direction, wherein the c axis of the crystals was globally ordered parallel to the shear direction. The sheared and patterned PVDF-TrFE thin films are readily incorporated into non-volatile memory units of metal/ferroelectric/metal capacitors and bottom gate-top contact field effect transistors, leading to arrays of memory devices with enhanced performance.