Nanoscale Electronic Inhomogeneity in In2Se3 Nanoribbons Revealed by Microwave Impedance Microscopy

TL;DR

This study uses microwave impedance microscopy to reveal nanoscale electronic inhomogeneity in In2Se3 nanoribbons, identifying multiple phases with vastly different resistivities and demonstrating local phase change memory effects.

Contribution

First application of near-field microwave impedance microscopy to directly image electronic inhomogeneity in In2Se3 nanoribbons at nanoscale.

Findings

Multiple phases with resistivity differences of six orders of magnitude identified

Inhomogeneous length scale of 100 nm observed

Phase change memory effects recorded locally with opposite signals

Abstract

Driven by interactions due to the charge, spin, orbital, and lattice degrees of freedom, nanoscale inhomogeneity has emerged as a new theme for materials with novel properties near multiphase boundaries. As vividly demonstrated in complex metal oxides and chalcogenides, these microscopic phases are of great scientific and technological importance for research in high-temperature superconductors, colossal magnetoresistance effect, phase-change memories, and domain switching operations. Direct imaging on dielectric properties of these local phases, however, presents a big challenge for existing scanning probe techniques. Here, we report the observation of electronic inhomogeneity in indium selenide (In2Se3) nanoribbons by near-field scanning microwave impedance microscopy. Multiple phases with local resistivity spanning six orders of magnitude are identified as the coexistence of superlattice, simple hexagonal lattice and amorphous structures with 100nm inhomogeneous length scale, consistent with high-resolution transmission electron microscope studies. The atomic-force-microscope-compatible microwave probe is able to perform quantitative sub-surface electronic study in a noninvasive manner. Finally, the phase change memory function in In2Se3 nanoribbon devices can be locally recorded with big signal of opposite signs.