scholarly journals Simulation of the Impact of Ionized Impurity Scattering on the Total Mobility in Si Nanowire Transistors

Materials ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 124 ◽  
Author(s):  
Toufik Sadi ◽  
Cristina Medina-Bailon ◽  
Mihail Nedjalkov ◽  
Jaehyun Lee ◽  
Oves Badami ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Small Diameter ◽  
Golden Rule ◽  
Impurity Scattering ◽  
Boltzmann Transport ◽  
Nanowire Transistors ◽  
Scattering Mechanisms ◽  
Relaxation Time Approximation ◽  
Ionized Impurity Scattering ◽  
The Impact

Nanowire transistors (NWTs) are being considered as possible candidates for replacing FinFETs, especially for CMOS scaling beyond the 5-nm node, due to their better electrostatic integrity. Hence, there is an urgent need to develop reliable simulation methods to provide deeper insight into NWTs’ physics and operation, and unlock the devices’ technological potential. One simulation approach that delivers reliable mobility values at low-field near-equilibrium conditions is the combination of the quantum confinement effects with the semi-classical Boltzmann transport equation, solved within the relaxation time approximation adopting the Kubo–Greenwood (KG) formalism, as implemented in this work. We consider the most relevant scattering mechanisms governing intraband and multi-subband transitions in NWTs, including phonon, surface roughness and ionized impurity scattering, whose rates have been calculated directly from the Fermi’s Golden rule. In this paper, we couple multi-slice Poisson–Schrödinger solutions to the KG method to analyze the impact of various scattering mechanisms on the mobility of small diameter nanowire transistors. As demonstrated here, phonon and surface roughness scattering are strong mobility-limiting mechanisms in NWTs. However, scattering from ionized impurities has proved to be another important mobility-limiting mechanism, being mandatory for inclusion when simulating realistic and doped nanostructures, due to the short range Coulomb interaction with the carriers. We also illustrate the impact of the nanowire geometry, highlighting the advantage of using circular over square cross section shapes.

Low-temperature operation of junctionless nanowire transistors: Less surface roughness scattering effects and dominant scattering mechanisms

2014 ◽  
Vol 105 (26) ◽  
pp. 263505 ◽  
Author(s):  
Dae-Young Jeon ◽  
So Jeong Park ◽  
Mireille Mouis ◽  
Sylvain Barraud ◽  
Gyu-Tae Kim ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Low Temperature ◽  
Nanowire Transistors ◽  
Scattering Mechanisms ◽  
Surface Roughness Scattering ◽  
Scattering Effects

Analysis of Gate Oxide Nitridation Effect on SiC MOSFETs by Using Hall Measurement and Split C–V Measurement

2016 ◽  
Vol 858 ◽  
pp. 441-444 ◽  
Author(s):  
Masatoshi Tsujimura ◽  
Hidenori Kitai ◽  
Hiromu Shiomi ◽  
Kazutoshi Kojima ◽  
Kenji Fukuda ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Hall Mobility ◽  
Impurity Scattering ◽  
Gate Oxide ◽  
Trap Density ◽  
Oxide Semiconductor ◽  
Free Carriers ◽  
Scattering Mechanisms ◽  
Ionized Impurity Scattering ◽  
Similar Temperature

In this study, 4H–SiC inversion layers were experimentally evaluated by Hall and split C–V measurements, and scattering mechanisms related to gate oxide nitridation were analyzed. Three typical samples with different crystal plane directions and gate oxidation conditions were prepared, and their total trap density and Hall mobility were compared. Based on the temperature dependence of the Hall mobility, we found that scattering mechanisms differed for each sample. The sample C-face oxynitride which had a high nitrogen density at the metal–oxide–semiconductor (MOS) interface, showed a similar temperature dependency to that of ionized impurity scattering. This result suggests that high-density nitrogen acts as donors that supply free carriers and cause ionized impurity scattering, just like in a bulk crystal. In addition, the sample C-face wet has lowest influence of the Coulomb scattering because of the lowest temperature dependence of Hall mobility and the lowest total trap density.

A Split-Flux Model for Phonon Transport Near Hotspots

2004 ◽  
Author(s):  
S. Sinha ◽  
E. Pop ◽  
K. E. Goodson
Keyword(s):  
Electric Fields ◽  
Phonon Scattering ◽  
Semiconductor Device ◽  
Longitudinal Optical ◽  
Phonon Transport ◽  
Boltzmann Transport ◽  
Phonon Modes ◽  
Relaxation Time Approximation ◽  
Occupation Numbers ◽  
The Impact

Intense electron-phonon scattering near the peak electric field in a semiconductor device results in nanometer-scale phonon hotspots with power densities on the order of 1 W/μm3. To study the impact of the hotspot on phonon transport, we solve the phonon Boltzmann transport equation under the relaxation time approximation to yield the departure from equilibrium amongst phonon modes. The departure function is split into two contributions: one arising from the far-from-equilibrium emitted phonons and the other from the near-equilibrium thermal phonons. The model predictions are compared with existing data on ballistic phonon transport in silicon. Computations of transient and steady state phonon occupation numbers for a device geometry show the predominance of longitudinal optical phonons for electric fields on the order of 1 MV/m. Due to the low group velocity of these modes, there is an energy stagnation at the hotspot which results in an excess temperature rise of about 13% for a 90 nm bulk silicon device. During device switching, emitted phonons have sufficient time to relax completely when the duty cycle is 30% on a period of 100 ps.

THERMOELECTRIC AND THERMOMAGNETIC PROPERTIES OF GRAPHENE IN THE PRESENCE OF DIFFERENT SCATTERING PROCESSES

2013 ◽  
Vol 27 (09) ◽  
pp. 1350060 ◽  
Author(s):  
SAHAR IZADI ◽  
H. RAHIMPOUR SOLEIMANI
Keyword(s):  
Magnetic Field ◽  
Figure Of Merit ◽  
Phonon Scattering ◽  
Impurity Scattering ◽  
Charge Carrier Density ◽  
Boltzmann Transport ◽  
Relaxation Time Approximation ◽  
Thermomagnetic Properties ◽  
Charged Impurity Scattering ◽  
The Magnetic Field

Thermoelectric and thermomagnetic properties of graphene are analyzed using Boltzmann transport equation within the relaxation time approximation. Influence of temperature, charge carrier density and magnetic field on the thermopower and figure of merit is taken into account in the presence of different scattering processes. It is observed the magnetic field results in the increase of thermopower and figure of merit in the acoustical phonon scattering process, while they are reduced by charged impurity scattering.

CALCULATION OF THE ELECTRON DRIFT MOBILITY IN Cr2+:ZnS AND Cr2+:ZnSe MATERIALS BY RODE ITERATION MODEL

2010 ◽  
Vol 01 (04) ◽  
pp. 469-475 ◽  
Author(s):  
HADI ARABSHAHI
Keyword(s):  
Impurity Scattering ◽  
Electron Drift ◽  
Deformation Potential ◽  
Material Parameters ◽  
Free Carriers ◽  
Relaxation Time Approximation ◽  
Ionized Impurity Scattering ◽  
Different Temperatures ◽  
Iteration Model ◽  
Electron Drift Mobility

The results of electron drift velocity in Cr2+:ZnS , and Cr2+:ZnSe are calculated for different temperatures, free-electron concentrations and compositions. The two-mode nature of the polar optic phonons is considered jointly with deformation potential acoustic, piezoelectric, alloy and ionized-impurity scattering. Band non-parabolocity, admixture of p functions, arbitrary degeneracy of the electron distribution, and the screening effects of free carriers on the scattering probabilities are incorporated. The Boltzmann equation is solved by an iterative technique using the currently established values of the material parameters. The iterative results are in fair agreement with other recent calculations obtained using the relaxation-time approximation and experimental methods.

scholarly journals Smoothing additive manufactured parts using ns-pulsed laser radiation

2021 ◽  
Author(s):  
Florian Kuisat ◽  
Fernando Lasagni ◽  
Andrés Fabián Lasagni
Keyword(s):  
Surface Roughness ◽  
Mechanical Performance ◽  
State Of The Art ◽  
Pulsed Laser ◽  
Industrial Applications ◽  
Laser Source ◽  
Pulsed Laser Radiation ◽  
Current State ◽  
The Impact

AbstractIt is well known that the surface topography of a part can affect its mechanical performance, which is typical in additive manufacturing. In this context, we report about the surface modification of additive manufactured components made of Titanium 64 (Ti64) and Scalmalloy®, using a pulsed laser, with the aim of reducing their surface roughness. In our experiments, a nanosecond-pulsed infrared laser source with variable pulse durations between 8 and 200 ns was applied. The impact of varying a large number of parameters on the surface quality of the smoothed areas was investigated. The results demonstrated a reduction of surface roughness Sa by more than 80% for Titanium 64 and by 65% for Scalmalloy® samples. This allows to extend the applicability of additive manufactured components beyond the current state of the art and break new ground for the application in various industrial applications such as in aerospace.

Nature instigated Grey wolf algorithm for parametric optimization during machining (Milling) of polymer nanocomposites

2021 ◽  
pp. 089270572199320
Author(s):  
Prakhar Kumar Kharwar ◽  
Rajesh Kumar Verma
Keyword(s):  
Surface Roughness ◽  
Cutting Force ◽  
Polymer Nanocomposites ◽  
Feed Rate ◽  
Fitness Function ◽  
Depth Of Cut ◽  
Multiwall Carbon Nanotube ◽  
Grey Wolf ◽  
Milling Characteristics ◽  
The Impact

The new era of engineering society focuses on the utilization of the potential advantage of carbon nanomaterials. The machinability facets of nanocarbon materials are passing through an initial stage. This article emphasizes the machinability evaluation and optimization of Milling performances, namely Surface roughness (Ra), Cutting force (Fc), and Material removal rate (MRR) using a recently developed Grey wolf optimization algorithm (GWOA). The Taguchi theory-based L27 orthogonal array (OA) was employed for the Machining (Milling) of polymer nanocomposites reinforced by Multiwall carbon nanotube (MWCNT). The second-order polynomial equation was intended for the analysis of the model. These mathematical models were used as a fitness function in the GWOA to predict machining performances. The ANOVA outcomes efficiently explore the impact of machine parameters on Milling characteristics. The optimal combination for lower surface roughness value is 1.5 MWCNT wt.%, 1500 rpm of spindle speed, 50 mm/min of feed rate, and 3 mm depth of cut. For lower cutting force, 1.0 wt.%, 1500 rpm, 90 mm/min feed rate and 1 mm depth of cut and the maximize MRR was acquired at 0.5 wt.%, 500 rpm, 150 mm/min feed rate and 3 mm depth of cut. The deviation of the predicted value from the experimental value of Ra, Fc, and MRR are found as 2.5, 6.5 and 5.9%, respectively. The convergence plot of all Milling characteristics suggests the application potential of the GWO algorithm for quality improvement in a manufacturing environment.

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