65 research outputs found
Silicon-etalon fiber-optic temperature sensor
A temperature sensor is described which consists of a silicon etalon that is sputtered directly onto the end of an optical fiber. A two-layer protective cap structure is used to improve the sensor's long-term stability. The sensor's output is wavelength encoded to provide a high degree of immunity from cable and connector effects. This sensor is extremely compact and potentially inexpensive
Modeling of a Cantilever-Based Near-Field Scanning Microwave Microscope
We present a detailed modeling and characterization of our scalable microwave
nanoprobe, which is a micro-fabricated cantilever-based scanning microwave
probe with separated excitation and sensing electrodes. Using finite-element
analysis, the tip-sample interaction is modeled as small impedance changes
between the tip electrode and the ground at our working frequencies near 1GHz.
The equivalent lumped elements of the cantilever can be determined by
transmission line simulation of the matching network, which routes the
cantilever signals to 50 Ohm feed lines. In the microwave electronics, the
background common-mode signal is cancelled before the amplifier stage so that
high sensitivity (below 1 atto-Farad capacitance changes) is obtained.
Experimental characterization of the microwave probes was performed on
ion-implanted Si wafers and patterned semiconductor samples. Pure electrical or
topographical signals can be realized using different reflection modes of the
probe.Comment: 7 figure
Human-Machine Interface for Tele-Robotic Operation: Mapping of Tongue Movements Based on Aural Flow Monitoring
2004 IEEE International Conference on Intelligent Robots and Systems (IROS), October, 2004 (Awarded “Best Paper in Conference”
Electrical Characterization of Defects in SiC Schottky Barriers
We have been investigating the effect of screw dislocation and other structural defects on the electrical properties of SiC. SiC is a wide-bandgap semiconductor that is currently received much attention due to its favorable high temperature behavior and high electric field breakdown strength. Unfortunately, the current state-of-the-art crystal growth and device processing methods produce material with high defect densities, resulting in a limited commercial viabilit
Nanoscale Electronic Inhomogeneity in In2Se3 Nanoribbons Revealed by Microwave Impedance Microscopy
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
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