Shear-Induced Ordering of Ferroelectric Crystals in Spin-Coated Thin Poly(vinylidene fluoride-co-trifluoroethylene) Films

Abstract

We present a robust route for fabricating a thin ferroelectric poly(vinylidene fluoride-cotrifluoroethylene) (PVDF-TrFE) film with both molecular and microstructural crystal ordering over the area of 1 Â 1 cm 2 . The method is based on the static mechanical shearing of the film under appropriate thermal conditions. The apparatus designed particularly for ultrathin PVDF-TrFE films with thickness of 200 nm or less allowed us to fabricate a thin film with ca. 25 nm thick crystalline lamellae globally ordered perpendicular to the shear direction. Grazing incident X-ray diffraction and polarized near edge X-ray absorption fine structure further revealed the molecular orientation of the crystals with c and a axes of the PVDF-TrFE crystals preferentially oriented parallel to shear direction and film surface normal, respectively. The shearing of a thin film at 135 °C gave rise to the best crystal orientation directly correlated with approximately 50% enhanced ferroelectric polarization observed in a metal/sheared PVDF-TrFE/metal capacitor.

Internal stresses and formation of switchable nanowires at thin silica film edges

“…External evidence for shear-induced deformations of vertical edge interfaces is shown in Fig. 2(c spin-coated thin film polymers 17 and by disappearance of stress singularities at interface edges in vertically nanostructured thin film columnar oxides 18 . It has also been calculated by a finite element analysis for two types of components with different interface edges between the thin film and substrate 18 (see Fig.…”

Improving information density in ferroelectric polymer films by using nanoimprinted gratings

“…By using these nanogratings, an improved management of writing and reading information of about 500 Gbit/in. 2 (0.01 bit/nm 2 ) can be reached as revealed by Piezoresponse Force Microscopy. Structural investigation by means of X-ray diffraction techniques indicates that the physical confinement generated by nanoimprint promotes the development of smaller and edge-on oriented crystals.…”

“…perpendicular to the surface. 2 On the other hand, a high intensity on the meridian indicates the existence of edge-on lamellae with polymer chains lying on the substrate. 9 AFM/SEM images and GIWAXS indicate that the P(VDF-TrFE) thin films consist of a mixture of flat-on and edge-on lamellae with some degree of tilting.…”

“…2,33,34 These two reflections are separated 60 from one another in a hk0 diffraction pattern. 2 The intensity distribution on the observed semi-ring ( Fig. 3(a)) can be used to characterize both polymer chain and lamellae orientation on these thin films.…”

“…Several approaches and prototypes have already been proposed, for example, metalpolymer-metal capacitors, [1][2][3][4][5] field-effect transistors, 6-9 and tunnel-junctions, 10 all of them based on thin polymer films, generally with thickness smaller than 100 nm, and with the possibility of a readily integration with flexible complementary metal oxide semiconductor devices or other organic electronic devices.…”