796 research outputs found
Monte Carlo Modeling of Spin FETs Controlled by Spin-Orbit Interaction
A method for Monte Carlo simulation of 2D spin-polarized electron transport
in III-V semiconductor heterojunction FETs is presented. In the simulation, the
dynamics of the electrons in coordinate and momentum space is treated
semiclassically. The density matrix description of the spin is incorporated in
the Monte Carlo method to account for the spin polarization dynamics. The
spin-orbit interaction in the spin FET leads to both coherent evolution and
dephasing of the electron spin polarization. Spin-independent scattering
mechanisms, including optical phonons, acoustic phonons and ionized impurities,
are implemented in the simulation. The electric field is determined
self-consistently from the charge distribution resulting from the electron
motion. Description of the Monte Carlo scheme is given and simulation results
are reported for temperatures in the range 77-300 K.Comment: 18 pages, 7 figure
Gate-controlled reversible rectifying behaviour in tunnel contacted atomically-thin MoS transistor
Atomically-thin 2D semiconducting materials integrated into van der Waals
heterostructures have enabled architectures that hold great promise for next
generation nanoelectronics. However, challenges still remain to enable their
full acceptance as compliant materials for integration in logic devices. Two
key-components to master are the barriers at metal/semiconductor interfaces and
the mobility of the semiconducting channel, which endow the building-blocks of
diode and field effect transistor. Here, we have devised a reverted
stacking technique to intercalate a wrinkle-free h-BN tunnel layer between
MoS channel and contacting electrodes. Vertical tunnelling of electrons
therefore makes it possible to suppress the Schottky barriers and Fermi level
pinning, leading to homogeneous gate-control of the channel chemical potential
across the bandgap edges. The observed unprecedented features of ambipolar
to diode, which can be reversibly gate tuned, paves the way for
future logic applications and high performance switches based on atomically
thin semiconducting channel.Comment: 23 pages, 5 main figures + 9 SI figure
High magnetoresistance at room temperature in p-i-n graphene nanoribbons due to band-to-band tunneling effects
A large magnetoresistance effect is obtained at room-temperature by using
p-i-n armchair-graphene-nanoribbon (GNR) heterostructures. The key advantage is
the virtual elimination of thermal currents due to the presence of band gaps in
the contacts. The current at B=0T is greatly decreased while the current at
B>0T is relatively large due to the band-to-band tunneling effects, resulting
in a high magnetoresistance ratio, even at room-temperature. Moreover, we
explore the effects of edge-roughness, length, and width of GNR channels on
device performance. An increase in edge-roughness and channel length enhances
the magnetoresistance ratio while increased channel width can reduce the
operating bias.Comment: http://dx.doi.org/10.1063/1.362445
A simple one-dimensional model for the explanation and analysis of GaAs MESFET behavior
The explanation of GaAs metal-semiconductor field effect transistor (MESFET) operation often involves the use of simplistic analytical formulae, which serve to obscure the more subtle physics of device action. The authors consider here a simple one-dimensional (1-D) model for GaAs MESFETs, which avoids more confusing numerical modeling schemes, yet still facilitates an analysis of the physical functionality of the device. The model takes into account current saturation due to either velocity saturation or channel pinch-off, the modulation of effective gate length and the series resistance of the regions beyond the gate. The results of the model have been compared to experimental data readily obtained from the literature, and the agreement has been shown to be goo
Characterization of the mechanisms of charge Trapping in GaN Vertical devices
In this master thesis a new type of transistor is analyzed: the GaN Vertical Fin FET Transistor. This kind of transistor is made on GaN, a wide bandgap semiconductor which is a promising material for the future power electronics . Fin FET Transistor is based on a fin-architecture and the current flows vertically through a GaN made nanometer-sized channel having a MOS stack on the sides. In this work different measurements are performed in order to see the variation of the threshold voltage and channel resistance of the transistor varying the fin width and external parameters such as temperature and exposure to UV-light. Oxide trapping phenomena are analysed by applying to the gate an increasing positive bias potential and for increasing periods of time. Simulations are performed in order to further analyze the results and give an extensive explanation of the charge trapping behaviour in different bias conditions.ope
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