Effects of annealing conditions on ferroelectric nanomesa self-assembly

Abstract

We report the results of studies of the effects of annealing conditions on the morphology of ferroelectric nanomesas. The nanomesa patterns were fabricated by self-assembly from continuous ultra-thin Langmuir-Blodgett fi lms of copolymers of vinylidene fl uoride and trifl uoroethylene. Annealing in the paraelectric phase induced surface reorganization into disc-shaped ferroelectric nanomesas approximately 9 nm thick and 100 nm in diameter. Several factors affect the nanomesa dimensions, such as polymer composition, substrate material, deposition conditions, and annealing temperature. The height and diameter of the nanomesas both increase with increasing annealing temperature. Annealing studies in the ferroelectric-paraelectric coexistence region show that only the paraelectric phase is mobile. From this we conclude that the paraelectric phase supports a kind of plastic crystalline fl ow connected with dynamic disorder of the polymer conformation.

Orientational imaging in polar polymers by piezoresponse force microscopy

“…Annealing of the initially continuous ultrathin LB films of P(VDF-TrFE) copolymers results in the spontaneous appearance of isolated highly crystalline nanomesas with the lateral dimensions in the range from 100 nm to 500 nm. 17 The topographic image in Fig. 1 images of nanomesas associated with the out-of-plane component of polarization.…”

Nanoscale domain patterns in ultrathin polymer ferroelectric films

“…Film morphology and grain sizes were controlled by subjecting the films to additional annealing under the same conditions as above. Detailed studies of the effect of annealing conditions on P(VDF-TrFE) film morphology are reported in [15,16]. In piezoresponse imaging of ferroelectrics, a periodic bias V tip = V 0 cos ωt with amplitude V 0 well below the coercive voltage is applied to the probing tip in contact with the surface.…”

Fabrication of diisopropylammonium bromide aligned microcrystals with in-plane uniaxial polarization

“…Another class of useful ferroelectrics is polymers [19], most notably those based on vinylidene fluoride (VDF) [20,21]. Copolymers of VDF with trifluoroethylene (TrFE), P(VDF-TrFE), for example, have become the ferroelectric polymer of choice for applications, due in part to the variety of ways they can be prepared in bulk using inexpensive solution-processing methods [22] and can be formed into high-performance thin films and nanostructures [21,[23][24][25][26][27]. The ferroelectric polymers, however, have not proven particularly amenable to synthetic modification for optimizing ferroelectric properties in the way the ferroelectric oxides have [28].…”