292 research outputs found
Electrical Nanoprobing of Semiconducting Carbon Nanotubes using an Atomic Force Microscope
We use an Atomic Force Microscope (AFM) tip to locally probe the electronic
properties of semiconducting carbon nanotube transistors. A gold-coated AFM tip
serves as a voltage or current probe in three-probe measurement setup. Using
the tip as a movable current probe, we investigate the scaling of the device
properties with channel length. Using the tip as a voltage probe, we study the
properties of the contacts. We find that Au makes an excellent contact in the
p-region, with no Schottky barrier. In the n-region large contact resistances
were found which dominate the transport properties.Comment: 4 pages, 5 figure
Study of natural formation and anthropogenic change in soils for sustainable land-use
In this work, we have presented an approach to rational territorial organization of the environment with the aim of harmonizing natural, economic and socio-demographic processes. Successive stages of the action for the development of basin nature management projects are proposed by us. Design technology rational land use is implemented for one of the small river basi
RESEARCH OF PROBLEMS OF INFORMATION SUPPORT OF PROCESSES OF LIFE CYCLE OF PRODUCTS
In article results of a research of opportunities of complex introduction of information systems and technologies in the industry are stated. The concept of support of processes of life cycle of production of products in borders of the integrated uniform information environment is fered. It is proved that integration of an automated control system for production consists in progressing of level of efficiency of creation and application of high technologies in production. Organizational and economic problems of introduction of information technologies are allocated, and the complete strategy of the modern organization of process of production within a common information space is offered
Selfoscillations of Suspended Carbon Nanotubes with a Deflection Sensitive Resistance under Voltage Bias
We theoretically investigate the electro-mechanics of a Suspended Carbon
Nanotube with a Deflection Sensitive Resistance subjected to a homogeneous
Magnetic Field and a constant Voltage Bias. We show that, (with the exception
of a singular case), for a sufficiently high magnetic field the
time-independent state of charge transport through the nanotube becomes
unstable to selfexcitations of the mechanical vibration accompanied by
oscialltions in the voltage drop and current across the nanotube.Comment: 4 pages, 1 figur
Capacitive Spring Softening in Single-Walled Carbon Nanotube Nanoelectromechanical Resonators
We report the capacitive spring softening effect observed in single-walled
carbon nanotube (SWNT) nanoelectromechanical (NEM) resonators. The nanotube
resonators adopt dual-gate configuration with both bottom-gate and side-gate
capable of tuning the resonance frequency through capacitive coupling.
Interestingly, downward resonance frequency shifting is observed with
increasing side-gate voltage, which can be attributed to the capacitive
softening of spring constant. Furthermore, in-plane vibrational modes exhibit
much stronger spring softening effect than out-of-plan modes. Our dual-gate
design should enable the differentiation between these two types of vibrational
modes, and open up new possibility for nonlinear operation of nanotube
resonators.Comment: 12 pages/ 3 figure
Electromechanical instability in suspended carbon nanotubes
We have theoretically investigated electromechanical properties of freely
suspended carbon nanotubes when a current is injected into the tubes using a
scanning tunneling microscope. We show that a shuttle-like electromechanical
instability can occur if the bias voltage exceeds a dissipation-dependent
threshold value. An instability results in large amplitude vibrations of the
carbon nanotube bending mode, which modify the current-voltage characteristics
of the system
Photocurrent Imaging of p-n Junctions and Local Defects in Ambipolar Carbon Nanotube Transistors
We use scanning photocurrent microscopy (SPCM) to investigate the properties
of internal p-n junctions as well as local defects in ambipolar carbon nanotube
(CNT) transistors. Our SPCM images show strong signals near metal contacts
whose polarity and positions change depending on the gate bias. SPCM images
analyzed in conjunction with the overall conductance also indicate the
existence and gate-dependent evolution of internal p-n junctions near contacts
in the n-type operation regime. To determine the p-n junction position and the
depletion width with a nanometer scale resolution, a Gaussian fit was used. We
also measure the electric potential profile of CNT devices at different gate
biases, which shows that both local defects and induced electric fields can be
imaged using the SPCM technique. Our experiment clearly demonstrates that SPCM
is a valuable tool for imaging and optimizing electrical and optoelectronic
properties of CNT based devices.Comment: 5 pages, 5 figure
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