1,420 research outputs found
Evaluation of a gate capacitance in the sub-aF range for a chemical field-effect transistor with a silicon nanowire channel
An evaluation of the gate capacitance of a field-effect transitor (FET) whose
channel length and width are several ten nanometer, is a key point for sensors
applications. However, experimental and precise evaluation of capacitance in
the aF range or less has been extremely difficult. Here, we report an
extraction of the capacitance down to 0.55 aF for a silicon FET with a
nanoscale wire channel whose width and length are 15 and 50 nm, respectively.
The extraction can be achieved by using a combination of four kinds of
measurements: current characteristics modulated by double gates,
random-telegraph-signal noise induced by trapping and detrapping of a single
electron, dielectric polarization noise, and current characteristics showing
Coulomb blockade at low temperature. The extraction of such a small gate
capacitance enables us to evaluate electron mobility in a nanoscale wire using
a classical model of current characteristics of a FET.Comment: To be published in IEEE Trans. Nanotechno
One-by-one trap activation in silicon nanowire transistors
Flicker or 1/f noise in metal-oxide-semiconductor field-effect transistors
(MOSFETs) has been identified as the main source of noise at low frequency. It
often originates from an ensemble of a huge number of charges trapping and
detrapping. However, a deviation from the well-known model of 1/f noise is
observed for nanoscale MOSFETs and a new model is required. Here, we report the
observation of one-by-one trap activation controlled by the gate voltage in a
nanowire MOSFET and we propose a new low-frequency-noise theory for nanoscale
FETs. We demonstrate that the Coulomb repulsion between electronically charged
trap sites avoids the activation of several traps simultaneously. This effect
induces a noise reduction by more than one order of magnitude. It decreases
when increasing the electron density in the channel due to the electrical
screening of traps. These findings are technologically useful for any FETs with
a short and narrow channel.Comment: One file with paper and supplementary informatio
Impurity conduction in phosphorus-doped buried-channel silicon-on-insulator field-effect transistors
We investigate transport in phosphorus-doped buried-channel
metal-oxide-semiconductor field-effect transistors at temperatures between 10
and 295 K. In a range of doping concentration between around 2.1 and 8.7 x 1017
cm-3, we find that a clear peak emerges in the conductance versus gate-voltage
curves at low temperature. In addition, temperature dependence measurements
reveal that the conductance obeys a variable-range-hopping law up to an
unexpectedly high temperature of over 100 K. The symmetric dual-gate
configuration of the silicon-on-insulator we use allows us to fully
characterize the vertical-bias dependence of the conductance. Comparison to
computer simulation of the phosphorus impurity band depth-profile reveals how
the spatial variation of the impurity-band energy determines the hopping
conduction in transistor structures. We conclude that the emergence of the
conductance peak and the high-temperature variable-range hopping originate from
the band bending and its change by the gate bias. Moreover, the peak structure
is found to be strongly related to the density of states (DOS) of the
phosphorus impurity band, suggesting the possibility of performing a novel
spectroscopy for the DOS of phosphorus, the dopant of paramount importance in
Si technology, through transport experiments.Comment: 9 figure
Electrically driven single electron spin resonance in a slanting Zeeman field
The rapidly rising fields of spintronics and quantum information science have
led to a strong interest in developing the ability to coherently manipulate
electron spins. Electron spin resonance (ESR) is a powerful technique to
manipulate spins that is commonly achieved by applying an oscillating magnetic
field. However, the technique has proven very challenging when addressing
individual spins. In contrast, by mixing the spin and charge degrees of freedom
in a controlled way through engineered non-uniform magnetic fields, electron
spin can be manipulated electrically without the need of high-frequency
magnetic fields. Here we realize electrically-driven addressable spin rotations
on two individual electrons by integrating a micron-size ferromagnet to a
double quantum dot device. We find that the electrical control and spin
selectivity is enabled by the micro-magnet's stray magnetic field which can be
tailored to multi-dots architecture. Our results demonstrate the feasibility of
manipulating electron spins electrically in a scalable way.Comment: 25 pages, 6 figure
Diamond semiconductor technology for RF device applications
This paper presents a comprehensive review of diamond electronics from the RF perspective. Our aim was to find and present the potential, limitations and current status of diamond semiconductor devices as well as to investigate its suitability for RF device applications. While doing this, we briefly analysed the physics and chemistry of CVD diamond process for a better understanding of the reasons for the technological challenges of diamond material. This leads to Figure of Merit definitions which forms the basis for a technology choice in an RF device/system (such as transceiver or receiver) structure. Based on our literature survey, we concluded that, despite the technological challenges and few mentioned examples, diamond can seriously be considered as a base material for RF electronics, especially RF power circuits, where the important parameters are high speed, high power density, efficient thermal management and low signal loss in high power/frequencies. Simulation and experimental results are highly regarded for the surface acoustic wave (SAW) and field emission (FE) devices which already occupies space in the RF market and are likely to replace their conventional counterparts. Field effect transistors (FETs) are the most promising active devices and extremely high power densities are extracted (up to 30 W/mm). By the surface channel FET approach 81 GHz operation is developed. Bipolar devices are also promising if the deep doping problem can be solved for operation at room temperature. Pressure, thermal, chemical and acceleration sensors have already been demonstrated using micromachining/MEMS approach, but need more experimental results to better exploit thermal, physical/chemical and electronic properties of diamond
Quantum simulation of Fermi-Hubbard models in semiconductor quantum dot arrays
We propose a device for studying the Fermi-Hubbard model with long-range
Coulomb interactions using an array of quantum dots defined in a semiconductor
two-dimensional electron gas system. Bands with energies above the lowest
energy band are used to form the Hubbard model, which allows for an
experimentally simpler realization of the device. We find that depending on
average electron density, the system is well described by a one- or two-band
Hubbard model. Our device design enables the control of the ratio of the
Coulomb interaction to the kinetic energy of the electrons independently to the
filling of the quantum dots, such that a large portion of the Hubbard phase
diagram may be probed. Estimates of the Hubbard parameters suggest that a
metal-Mott insulator quantum phase transition and a d-wave superconducting
phase should be observable using current fabrication technologies.Comment: 12 pages, 3 figures, 1 table
Modeling and numerical analysis of beam matrix plasma display system
This research investigates a new display device - Beam Matrix Plasma Display Panel (BM PDP). The scan of a PDP in such a system is accomplished through two electrical-beam guns instead of semiconductor switches.
The BM-PDP eliminates the expensive semiconductor switches in the current plasma display device systems. Its drive circuit has only three parts: electron beam guns, resistors and capacitors. During the operation of BM PDP, first a switch cell is turned on by a selection gun (X gun). Then another electron gun (Y gun) emits electrons onto column electrodes and capacitors. When the voltage over the corresponding luminous cell reaches its breakdown point, gas discharges and generates light. Drive circuit design and analysis for BM-PDP is an important research topic. This work derives the formulae describing the operation of the drive circuit. With these formulae all the cases in which the drive circuit may work are discussed theoretically and numerically. Two equations are also given to determine the time of cell breakdown in these cases. The results of numerical simulation show that the current of an electron beam gun can be employed to carry the signal of image, the capacitance of a display cell is not sensitive to the initial current of gas discharge. The later property can be used to reduce the difficulties of manufacturing. The process of gas discharge in a display cell is also discussed and a multi-particle physical model is given to simulate the plasma cell
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