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.Comment: 11 pages, 4 figure