Piezo- and Ferroelectric Properties of Self-Assembled PbTiO₃ Nanoisland Structures Fabricated by Metalorganic Chemical Vapor Deposition

Abstract

TlBiS 2 is a narrow-gap semiconductor with a layered structure, isoelectronically analogous to PbS. Large single crystals were grown by the Bridgman-Stockbarger method from the melt and characterized by x-ray diffraction. The lattice parameters were determined and the discrepancy between those already reported was removed. From IR reflectivity measurements in the plasma region, the number of carriers was calculated. Also a strong anisotropy of the electrical conductivity was detected and the narrow-gap character of the material was supported by electrical measurements in the range of 10-300 K.

Size Dependence of Ferroelectric Properties of Epitaxial PbTiO₃ Nanoislands on Pt/SrTiO₃(100)

“…This is also supported by the fact that d 33,PFM drastically drops when the height is less than 10nm, which is roughly equal to the critical size of PbTiO 3 ultrafine particles [4][5][6]. Note that the critical height below which piezoresponse is not shown should be below 2nm because the height of nanoislands was at least 2nm and all nanoislands exhibited piezoresponse in this study [7,8,10].…”

“…Intrinsic size effects, in these reports, were not observed because the dimensions of islands fabricated by the top down methods were much larger than the size in which intrinsic size effects were observed in ultrafine particles [4][5][6]. On the other hand, ferroelectric islands with dimensions similar to the critical size of ultrafine particles have been successfully fabricated by the bottom up method [7][8][9][10]. The critical size in PbTiO 3 nanoislands was found to be 20nm in width and 1.2-8nm in height [7,8,10].…”

“…On the other hand, ferroelectric islands with dimensions similar to the critical size of ultrafine particles have been successfully fabricated by the bottom up method [7][8][9][10]. The critical size in PbTiO 3 nanoislands was found to be 20nm in width and 1.2-8nm in height [7,8,10]. However, the size dependence of ferroelectric and piezoelectric properties of nanoislands smaller than 100nm has not been well understood yet.…”

Unusual Polarization Patterns in Flat Epitaxial Ferroelectric Nanoparticles

“…While the authors [4,6] did not observe any piezoresponse of the PbTiO 3 islands with the diameters smaller than 20 nm, Ref. [5] reported observation of ferroelectricity in zirconate titanate nanoparticles with the lateral size as small as 9 nm.…”

“…Recent advances in the ''bottom-up'' (self-assembly) nanometer scale techniques have opened up the opportunities for fabricating highquality epitaxial ferroelectric nanoislands with extremely small thickness and lateral size on the order of 1 nm and 20 nm, respectively [3][4][5][6][7]. On the other hand, recent emergence of powerful probes such as piezoresponse force microscopy (PFM) has enabled imaging of a local domain structure with sub-10 nm resolution [2,8,9].…”