The Experts below are selected from a list of 279 Experts worldwide ranked by ideXlab platform
Hajime Okumura - One of the best experts on this subject based on the ideXlab platform.
-
Analysis of trench-filling epitaxial growth of 4H-SiC based on continuous fluid approximation including Gibbs-Thomson Effect
Materials Science Forum, 2017Co-Authors: Kazuhiro Mochizuki, Ryoji Kosugi, Kazutoshi Kojima, Yoshiyuki Yonezawa, Hajime OkumuraAbstract:Trench-filling epitaxial growth of 4H-SiC was analyzed based on a simulation model for continuous fluid approximation (as opposed to molecular beam approximation) including the Gibbs-Thomson Effect. With the use of the radii of curvature at the top and bottom of the trenches, the proposed model well reproduced the measured dependence of the growth rate on the trench pitch (L) in the case of narrow (L < 6.0 μm) trenches.
-
Numerical analysis of the Gibbs–Thomson Effect on trench-filling epitaxial growth of 4H-SiC
Applied Physics Express, 2016Co-Authors: Kazuhiro Mochizuki, Ryoji Kosugi, Kazutoshi Kojima, Yoshiyuki Yonezawa, Hajime OkumuraAbstract:A steady-state two-dimensional diffusion equation was numerically analyzed to examine the rate of homoepitaxial growth on a trenched 4H-SiC substrate. The radii of curvature at the top and bottom of the trenches were used to take the Gibbs?Thomson Effect into account in the analysis based on the conventional boundary-layer model. When the trench pitch was less than or equal to 6.0 ?m, the measured dependence of the growth rate on the trench pitch was found to be explained by the Gibbs?Thomson Effect on the vapor-phase diffusion of growing species.
-
numerical analysis of the gibbs Thomson Effect on trench filling epitaxial growth of 4h sic
Applied Physics Express, 2016Co-Authors: Kazuhiro Mochizuki, Ryoji Kosugi, Kazutoshi Kojima, Yoshiyuki Yonezawa, Hajime OkumuraAbstract:A steady-state two-dimensional diffusion equation was numerically analyzed to examine the rate of homoepitaxial growth on a trenched 4H-SiC substrate. The radii of curvature at the top and bottom of the trenches were used to take the Gibbs?Thomson Effect into account in the analysis based on the conventional boundary-layer model. When the trench pitch was less than or equal to 6.0 ?m, the measured dependence of the growth rate on the trench pitch was found to be explained by the Gibbs?Thomson Effect on the vapor-phase diffusion of growing species.
Eduard Feireisl - One of the best experts on this subject based on the ideXlab platform.
-
Regularization and symmetry breaking for the thermistor problem with the Thomson Effect
Meccanica, 1995Co-Authors: Giovanni Cimatti, Eduard FeireislAbstract:Si esamina un modello matematico per il dispositivo noto come termistore tenendo conto anche dell'effetto Thomson. Viene provato che il problema al contorno per il sistema di equazioni differenziali ordinario che regge il dispositivo ha sempre una e una sola soluzione a differenza di quanto accade quando l'effetto Thomson è transcurato. Si prova inoltre la perdita di simmetria della soluzione, fatto rilevato anche sperimentalmente. We examine a mathematical model of the thermistor taking into account the Thomson Effect. We show that this system of equations is always uniquely solvable, in sharp contrast with the case where the Thomson Effect is neglected. Another feature of the problem is breaking of the symmetry of the solutions in accordance with practical experiments.
-
Regularization and symmetry breaking for the thermistor problem with the Thomson Effect
Meccanica, 1995Co-Authors: Giovanni Cimatti, Eduard FeireislAbstract:We examine a mathematical model of the thermistor taking into account the Thomson Effect. We show that this system of equations is always uniquely solvable, in sharp contrast with the case where the Thomson Effect is neglected. Another feature of the problem is breaking of the symmetry of the solutions in accordance with practical experiments.
S C Kaushik - One of the best experts on this subject based on the ideXlab platform.
-
Thermodynamic analysis of thermoelectric generator including influence of Thomson Effect and leg geometry configuration
Energy Conversion and Management, 2017Co-Authors: Randeep Lamba, S C KaushikAbstract:To improve the power output and efficiency of the thermoelectric generator system, the variation in the thermoelectric leg configuration is another option. In this paper, the thermodynamic analysis of exoreversible thermoelectric generator including influence of Thomson Effect as well as influence of leg geometry on the power output and efficiency of the device has been carried out. The modified expressions for dimensionless figure of merit, power output, irreversibilities, energy and exergy efficiency considering Thomson Effect have been derived analytically. The Effects of various parameters such as dimensionless temperature ratio (θ), shape parameter (RA), Thomson Effect and load resistance ratio (RL/R0) on the power output, energy and exergy efficiency have been studied. The operating range for shape parameter has been found which improves the power output, energy and exergy efficiency of the device, however, the optimum operating point corresponding to maximum power output is different from that of the maximum energy and exergy efficiency. The results of this study shows that when the shape parameter is increased from 1 (flat plate TEG) to 2 (trapezoidal TEG), then the energy and exergy efficiency improve by 2.32% and 2.31% respectively with a 1.3% decrease in power output at RL/R0 = 10 and θ = 0.5. This study will help in designing of the improved thermoelectric generator systems for different leg geometries.
-
The influence of Thomson Effect in the performance optimization of a two stage thermoelectric generator
Energy, 2016Co-Authors: Sushmera Manikandan, S C KaushikAbstract:In this paper, the exoreversible and irreversible thermodynamic models of a TTEG (two stage thermoelectric Generator) considering Thomson Effect combined with Peltier, Joule and Fourier heat conduction have been investigated using exergy analysis. The expressions for interstage temperature, optimum current for the maximum power output condition and energy/exergy efficiency of a TTEG are derived. The number of thermocouples in the first and second stages of a TTEG for the maximum power output and energy/exergy efficiency conditions are optimized as well. The results show that the exergy efficiency of TTEG is greater than the energy efficiency. In an irreversible TTEG with 30 thermocouples, and with heat source temperature (TH) of 450 K and heat sink temperature (TC) of 300 K, the obtained maximum power output, maximum energy and exergy efficiency are 0.2996 W, 4.35% and 13.05% respectively. It has also been proved that the optimum number of thermocouples obtained in the first and second stages of a TTEG are different from the previous studies because of the influence of Thomson Effect. This study will help in the designing of the actual multistage thermoelectric generator systems.
-
The influence of Thomson Effect in the energy and exergy efficiency of an annular thermoelectric generator
Energy Conversion and Management, 2015Co-Authors: S C Kaushik, Sushmera ManikandanAbstract:The exoreversible thermodynamic model of an annular thermoelectric generator (ATEG) considering Thomson Effect in conjunction with Peltier, Joule and Fourier heat conduction has been investigated using exergy analysis. New expressions for optimum current at the maximum power output and maximum energy, exergy efficiency conditions, and dimensionless irreversibilities in the ATEG are derived. The modified expression for figure of merit of a thermoelectric generator considering the Thomson Effect has also been obtained. The results show that the power output, energy and exergy efficiency of the ATEG is lower than the flat plate thermoelectric generator. The Effects of annular shape parameter (Sr= r2/r1), load resistance (RL), dimensionless temperature ratio (θ = Th/Tc) and the thermal and electrical contact resistances in power output, energy/exergy efficiency of the ATEG have been studied. It has also been proved that because of the influence of Thomson Effect, the power output and energy/exergy efficiency of the ATEG is reduced. This study will help in the designing of the actual annular thermoelectric generation systems.
-
The influence of Thomson Effect in the performance optimization of a two stage thermoelectric cooler
Cryogenics, 2015Co-Authors: S C Kaushik, Sushmera ManikandanAbstract:Abstract The exoreversible and irreversible thermodynamic models of a two stage thermoelectric cooler (TTEC) considering Thomson Effect in conjunction with Peltier, Joule and Fourier heat conduction Effects have been investigated using exergy analysis. New expressions for the interstage temperature, optimum current for the maximum cooling power, energy and exergy efficiency conditions, energy efficiency and exergy efficiency of a TTEC are derived as well. The number of thermocouples in the first and second stages of a TTEC for the maximum cooling power, energy and exergy efficiency conditions are optimized. The results show that the exergy efficiency is lower than the energy efficiency e.g., in an irreversible TTEC with total 30 thermocouples, heat sink temperature ( T H ) of 300 K and heat source temperature ( T C ) of 280 K, the obtained maximum cooling power, maximum energy and exergy efficiency are 20.37 W, 0.7147 and 5.10% respectively. It has been found that the Thomson Effect increases the cooling power and energy efficiency of the TTEC system e.g., in the exoreversible TTEC the cooling power and energy efficiency increased from 14.87 W to 16.36 W and from 0.4079 to 0.4998 respectively for Δ T C of 40 K when Thomson Effect is considered. It has also been found that the heat transfer area at the hot side of an irreversible TTEC should be higher than the cold side for maximum performance operation. This study will help in the designing of the actual multistage thermoelectric cooling systems.
Kazuhiro Mochizuki - One of the best experts on this subject based on the ideXlab platform.
-
Analysis of trench-filling epitaxial growth of 4H-SiC based on continuous fluid approximation including Gibbs-Thomson Effect
Materials Science Forum, 2017Co-Authors: Kazuhiro Mochizuki, Ryoji Kosugi, Kazutoshi Kojima, Yoshiyuki Yonezawa, Hajime OkumuraAbstract:Trench-filling epitaxial growth of 4H-SiC was analyzed based on a simulation model for continuous fluid approximation (as opposed to molecular beam approximation) including the Gibbs-Thomson Effect. With the use of the radii of curvature at the top and bottom of the trenches, the proposed model well reproduced the measured dependence of the growth rate on the trench pitch (L) in the case of narrow (L < 6.0 μm) trenches.
-
Numerical analysis of the Gibbs–Thomson Effect on trench-filling epitaxial growth of 4H-SiC
Applied Physics Express, 2016Co-Authors: Kazuhiro Mochizuki, Ryoji Kosugi, Kazutoshi Kojima, Yoshiyuki Yonezawa, Hajime OkumuraAbstract:A steady-state two-dimensional diffusion equation was numerically analyzed to examine the rate of homoepitaxial growth on a trenched 4H-SiC substrate. The radii of curvature at the top and bottom of the trenches were used to take the Gibbs?Thomson Effect into account in the analysis based on the conventional boundary-layer model. When the trench pitch was less than or equal to 6.0 ?m, the measured dependence of the growth rate on the trench pitch was found to be explained by the Gibbs?Thomson Effect on the vapor-phase diffusion of growing species.
-
numerical analysis of the gibbs Thomson Effect on trench filling epitaxial growth of 4h sic
Applied Physics Express, 2016Co-Authors: Kazuhiro Mochizuki, Ryoji Kosugi, Kazutoshi Kojima, Yoshiyuki Yonezawa, Hajime OkumuraAbstract:A steady-state two-dimensional diffusion equation was numerically analyzed to examine the rate of homoepitaxial growth on a trenched 4H-SiC substrate. The radii of curvature at the top and bottom of the trenches were used to take the Gibbs?Thomson Effect into account in the analysis based on the conventional boundary-layer model. When the trench pitch was less than or equal to 6.0 ?m, the measured dependence of the growth rate on the trench pitch was found to be explained by the Gibbs?Thomson Effect on the vapor-phase diffusion of growing species.
H Mehdipour - One of the best experts on this subject based on the ideXlab platform.
-
minimizing the gibbs Thomson Effect in the low temperature plasma synthesis of thin si nanowires
Nanotechnology, 2011Co-Authors: H Mehdipour, Ken Ostrikov, Amanda Rider, Scott A. FurmanAbstract:An advanced combination of numerical models, including plasma sheath, ion- and radical-induced species creation and plasma heating Effects on the surface and within a Au catalyst nanoparticle, is used to describe the catalyzed growth of Si nanowires in the sheath of a low-temperature and low-pressure plasma. These models have been used to explain the higher nanowire growth rates, low-energy barriers, much thinner Si nanowire nucleation and the less Effective Gibbs–Thomson Effect in reactive plasma processes, compared with those of neutral gas thermal processes. The Effects of variation in the plasma sheath parameters and substrate potential on Si nanowire nucleation and growth have also been investigated. It is shown that increasing the plasma-related Effects leads to decreases in the nucleation energy barrier and the critical nanoparticle radius, with the Gibbs–Thomson Effect diminished, even at low temperatures. The results obtained are consistent with available experimental results and open a path toward the energy- and matter-efficient nucleation and growth of a broad range of one-dimensional quantum structures.
-
Minimizing the Gibbs–Thomson Effect in the low-temperature plasma synthesis of thin Si nanowires
Nanotechnology, 2011Co-Authors: H Mehdipour, Ken Ostrikov, Amanda E. Rider, Scott A. FurmanAbstract:An advanced combination of numerical models, including plasma sheath, ion- and radical-induced species creation and plasma heating Effects on the surface and within a Au catalyst nanoparticle, is used to describe the catalyzed growth of Si nanowires in the sheath of a low-temperature and low-pressure plasma. These models have been used to explain the higher nanowire growth rates, low-energy barriers, much thinner Si nanowire nucleation and the less Effective Gibbs–Thomson Effect in reactive plasma processes, compared with those of neutral gas thermal processes. The Effects of variation in the plasma sheath parameters and substrate potential on Si nanowire nucleation and growth have also been investigated. It is shown that increasing the plasma-related Effects leads to decreases in the nucleation energy barrier and the critical nanoparticle radius, with the Gibbs–Thomson Effect diminished, even at low temperatures. The results obtained are consistent with available experimental results and open a path toward the energy- and matter-efficient nucleation and growth of a broad range of one-dimensional quantum structures.
