5,801 research outputs found
Experimental Study of the Effect of External Signal on Microwave Oscillations in a Nonrelativistic Electron Beam with Virtual Cathode
The effect of an external harmonic signal on the characteristics of microwave
generation in a nonrelativistic electron beam with virtual cathode (VC) formed
in a static retarding electric field (low-voltage vircator system) has been
experimentally studied. A significant increase in the vircator generation power
is observed when the frequency of the external signal is close to the frequency
of VC oscillations. At large detunings, a broadband chaotic generation is
observed.Comment: 3 pages, 2 figure
Humidity effects on tip-induced polarization switching in lithium niobate
Interest to ferroelectric materials has been increased significantly in last
decades due to development of new generation of nonlinear optical and data
storage devices. Scanning probe microscopy (SPM) can be used both for study of
domain structures with nanoscale spatial resolution and for writing the
isolated nanodomains by local application of the electric field. Tip-induced
switching in the ambient still needs experimental investigations and
theoretical explorations. Here we studied influence of the value of relative
humidity in the SPM chamber on the process of tip-induced polarization
switching. This phenomenon was attributed to existing of the water meniscus
between tip and the sample surface in humid atmosphere. Presented results are
important for further complex investigations of the ferroelectric materials and
their applications.Comment: 15 pages, 5 figures, Submitted to Applied Physics Letter
Electromechanical Probing of Ionic Currents in Energy Storage Materials
The electrochemical processes in energy storage materials are generally
linked with changes of molar volume of the host compound. Here, the frequency
dependent strain response of 1D electrochemically active systems to periodic
electric bias is analyzed. The sensitivity and resolution of these
electrochemical strain measurements are compared to the current-based
electrochemical impedance spectroscopy. The resolution and detection limits of
interferometric and atomic force microscopy based systems for probing
electrochemical reactions on the nanoscale are analyzed.Comment: 12 pages, 4 figures, 2 tables, 2 appendices, submitted to Appl. Phys.
Let
Carbon nanotubes as a tip calibration standard for electrostatic scanning probe microscopies
Scanning Surface Potential Microscopy (SSPM) is one of the most widely used
techniques for the characterization of electrical properties at small
dimensions. Applicability of SSPM and related electrostatic scanning probe
microscopies for imaging of potential distributions in active micro- and
nanoelectronic devices requires quantitative knowledge of tip surface contrast
transfer. Here we demonstrate the utility of carbon-nanotube-based circuits to
characterize geometric properties of the tip in the electrostatic scanning
probe microscopies (SPM). Based on experimental observations, an analytical
form for the differential tip-surface capacitance is obtained.Comment: 14 pages, 4 figure
Tip-gating Effect in Scanning Impedance Microscopy of Nanoelectronic Devices
Electronic transport in semiconducting single-wall carbon nanotubes is
studied by combined scanning gate microscopy and scanning impedance microscopy
(SIM). Depending on the probe potential, SIM can be performed in both invasive
and non-invasive mode. High-resolution imaging of the defects is achieved when
the probe acts as a local gate and simultaneously an electrostatic probe of
local potential. A class of weak defects becomes observable even if they are
located in the vicinity of strong defects. The imaging mechanism of tip-gating
scanning impedance microscopy is discussed.Comment: 11 pages, 3 figures, to be published in Appl. Phys. Let
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