Chemically synthesized metal–oxide–metal segmented nanowires with high ferroelectric response

Abstract

A chemical synthesis method is presented for the fabrication of high-definition segmented metal-oxide-metal (MOM) nanowires in two different ferroelectric oxide systems: Au-BaTiO(3)-Au and Au-PbTiO(3)-Au. This method entails electrodeposition of segmented nanowires of Au-TiO(2)-Au inside anodic aluminum oxide (AAO) templates, followed by topotactic hydrothermal conversion of the TiO(2) segments into BaTiO(3) or PbTiO(3) segments. Two-terminal devices from individual MOM nanowires are fabricated, and their ferroelectric properties are measured directly, without the aid of scanning probe microscopy (SPM) methods. The MOM nanowire architecture provides high-quality end-on electrical contacts to the oxide segments, and allows direct measurement of properties of nanoscale volume, strain-free oxide segments. Unusually high ferroelectric responses, for chemically synthesized oxides, in these MOM nanowires are reported, and are attributed to the lack of residual strain in the oxides. The ability to measure directly the active properties of nanoscale volume, strain-free oxides afforded by the MOM nanowire architecture has important implications for fundamental studies of not only ferroelectric nanostructures but also nanostructures in the emerging field of multiferroics.

One‐Dimensional Nanostructures of Ferroelectric Perovskites

“…Advantages are that arrays of nanotubes can be obtained, that up‐scaling is relatively easy, and that the dimensions of the 1D nanostructures are controlled by the pore size. By using more advanced template methods, it is also possible to fabricate segmented nanowires 116. It is also interesting to combine porous templates with hydrothermal processing to obtain single‐crystalline nanostructures, as demonstrated for LiFePO 4 nanorod arrays,197 avoiding the calcination step.…”

“…Hydrothermal conversion of TiO 2 has also been used to fabricate segmented metal–perovskite–metal nanowires 116. First, segmented Au‐TiO 2 ‐Au nanowires were made by electrodeposition inside AAO templates.…”

Bipolar resistive switching in individual Au–NiO–Au segmented nanowires

“…1 But there is a growing demand for high-density NVRAMs in electronics that are fast, reliable, energy efficient, and immune to read-write fatigue. 1͒ developed in our laboratories [23][24][25][26][27][28] are more representative of prototypical single ReRAM memory cells. 1 One such concept for nonvolatile resistive random access memory ͑ReRAM͒ that is being pursued very actively is electric-field induced resistance change in oxides, 2-4 such as NiO, [5][6][7][8][9][10][11] TiO 2 , 12-15 Fe 2 O 3 , 10 CuO, 16 and perovskites.…”