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1.
Effect of interface roughness on the carrier transport in germanium MOSFETs investigated by Monte Carlo method 下载免费PDF全文
Interface roughness strongly influences the performance
of germanium metal--organic--semiconductor field effect transistors
(MOSFETs). In this paper, a 2D full-band Monte Carlo simulator is
used to study the impact of interface roughness scattering on
electron and hole transport properties in long- and short- channel
Ge MOSFETs inversion layers. The carrier effective mobility in the
channel of Ge MOSFETs and the in non-equilibrium transport
properties are investigated. Results show that both electron and
hole mobility are strongly influenced by interface roughness
scattering. The output curves for 50~nm channel-length double gate n
and p Ge MOSFET show that the drive currents of n- and p-Ge MOSFETs
have significant improvement compared with that of Si n- and
p-MOSFETs with smooth interface between channel and gate dielectric.
The $82\%$ and $96\%$ drive current enhancement are obtained for the
n- and p-MOSFETs with the completely smooth interface. However, the
enhancement decreases sharply with the increase of interface
roughness. With the very rough interface, the drive currents of Ge
MOSFETs are even less than that of Si MOSFETs. Moreover, the
significant velocity overshoot also has been found in Ge MOSFETs. 相似文献
2.
《Comptes Rendus Physique》2016,17(10):1154-1160
It has been proposed for a long time now that the reduction of the thermal conductivity by reducing the phonon mean free path is one of the best way to improve the current performance of thermoelectrics. By measuring the thermal conductance and thermal conductivity of nanowires and thin films, we show different ways of increasing the phonon scattering from low-temperature up to room-temperature experiments. It is shown that playing with the geometry (constriction, periodic structures, nano-inclusions), from the ballistic to the diffusive limit, the phonon thermal transport can be severely altered in single crystalline semiconducting structures; the phonon mean free path is in consequence reduced. The diverse implications on thermoelectric properties will be eventually discussed. 相似文献
3.
A two-dimensional analytical subthreshold behavior model for junctionless dual-material cylindrical surrounding-gate MOSFETs 下载免费PDF全文
A two-dimensional analytical subthreshold behavior model for junctionless dual-material cylindrical surrounding- gate (JLDMCSG) metal-oxide-semiconductor field-effect transistors (MOSFETs) is proposed. It is derived by solving the two-dimensional Poisson's equation in two continuous cylindrical regions with any simplifying assumption. Using this analytical model, the subthreshold characteristics of JLDMCSG MOSFETs are investigated in terms of channel electro- static potential, horizontal electric field, and subthreshold current. Compared to junctionless single-material cylindrical surrounding-gate MOSFETs, JLDMCSG MOSFETs can effectively suppress short-channel effects and simultaneously im- prove carrier transport efficiency. It is found that the subthreshold current of JLDMCSG MOSFETs can be significantly reduced by adopting both a thin oxide and thin silicon channel. The accuracy of the analytical model is verified by its good agreement with the three-dimensional numerical simulator ISE TCAD. 相似文献
4.
V. A. Kozlov V. A. Verbus A. V. Nikolaev 《Bulletin of the Russian Academy of Sciences: Physics》2009,73(1):80-83
A quantum-mechanical calculation of the THz negative conductance of hot ballistic electrons in nanoscale semiconductor heterostructures has been performed. It is shown that quantum beats of the ballistic electron wave function induce an ac current in the structure, which can do negative work on the ac field. 相似文献
5.
We show that the wide distribution of time constants required to explain 1/ƒ noise in MOSFETs arises as a natural consequence of the multi-phonon model of carrier trapping into individual Si-SiO2 interface states. A new class of random telegraph signal found in the drain current of small-area silicon MOSFETs is described. These signals are a result of defect metastability and are shown to be a source of non-Gaussian noise. 相似文献
6.
On nanoscale, thermal conduction
is affected by system size. The reasons are
increased phonon scattering and changes in phonon group
velocity. In this paper, the in-plane thermal resistivity
of nanoscale silicon thin films is analyzed
by molecular dynamics (MD) techniques. Modifications
to the dispersion relation are calculated directly with
MD methods at high temperature. The results indicate that
the dispersion relation starts to change for very thin
films, at around two nanometers. The reasons are band folding
and phonon confinement.
Thermal resistivity is analyzed by the direct
non-equilibrium method, and the results are compared
to kinetic theory with modified dispersion relations. Thermal
resistivity is affected by both surface scattering and dispersion.
Moreover, in thin films, the characteristic vibrational frequency
decreases, which in standard anharmonic scattering models indicates
a longer relaxation time and affects the resistivity.
The results indicate that in very thin films, the resistivity becomes
highly anisotropic due to differences in surface scattering.
In two cases, surface scattering was found to be the most important mechanism
for increasing thermal resistivity, while in one case, phonon
confinement was found to increase resistivity more than surface
scattering. 相似文献
7.
Scattering mechanisms of charge carriers in Transparent Conducting Oxide (TCO) films have been analyzed theoretically. For the degenerate polycrystalline TCO films with relatively large crystallite sizes and high carrier concentrations (higher than 5 × 1018 cm–3), the depletion layers between crystallites are very thin compared to the crystallite sizes, and the grain boundary scattering on electrical carriers makes a small contribution to limit the mobility of the films. Instead of thermionic emission current, a tunneling current dominates the electron transport over grain boundaries. The Petritz model which is based on thermionic emission and extensively quoted in literature should not be applicable. The main scattering mechanisms for the TCO films are ionized impurity scattering in the low-temperature range and lattice vibration scattering in the high-temperature range. The ionized impurity scattering mobility is independent of temperature and the mobility due to thermal lattice vibration scattering is inversely proportional to the temperature. The results obtained from Hall measurements on our ZnO, ITO, SnO2 and SnO2:F films prepared with various methods supports the analysis. 相似文献
8.
Ling-Feng Mao 《Pramana》2009,72(2):407-414
Based on the analysis of the three-dimensional Schrödinger equation, the effects of quantum coupling between the transverse and the longitudinal components of channel electron motion on the performance of ballistic MOSFETs have been theoretically investigated by self-consistently solving the coupled Schrödinger-Poisson equations with the finite-difference method. The results show that the quantum coupling between the transverse and the longitudinal components of the electron motion can largely affect device performance. It suggests that the quantum coupling effect should be considered for the performance of a ballistic MOSFET due to the high injection velocity of the channel electron. 相似文献
9.
碳化硅功率MOSFET是宽禁带功率半导体器件的典型代表,具有优异的电气性能。基于低温环境下的应用需求,研究了1200 V碳化硅功率MOSFET在77.7 K至300 K温区的静/动态特性,定性分析了温度对碳化硅功率MOSFET性能的影响。实验结果显示,温度从300 K降低至77.7 K时,阈值电压上升177.24%,漏-源极击穿电压降低32.99%,栅极泄漏电流降低82.51%,导通电阻升高1142.28%,零栅压漏电流降低89.84%(300 K至125 K)。双脉冲测试显示,开通时间增大8.59%,关断时间降低16.86%,开关损耗增加48%。分析发现,碳化硅功率MOSFET较高的界面态密度和较差的沟道迁移率,是导致其在低温下性能劣化的主要原因。 相似文献
10.
We report observation of intrinsic inverse spin Hall effect in undoped GaAs multiple quantum wells with a sample temperature of 10 K. A transient ballistic pure spin current is injected by a pair of laser pulses through quantum interference. By time resolving the dynamics of the pure spin current, the momentum relaxation time is deduced, which sets the lower limit of the scattering time between electrons and holes. The transverse charge current generated by the pure spin current via the inverse spin Hall effect is simultaneously resolved. We find that the charge current is generated well before the first electron-hole scattering event. Generation of the transverse current in the scattering-free ballistic transport regime provides unambiguous evidence for the intrinsic inverse spin Hall effect. 相似文献
11.
12.
Hahn K Jobic H Kärger J 《Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics》1999,59(6):6662-6671
Scattering functions and full widths at half maximum for quasielastic neutron scattering (QENS) are calculated for diffusion in systems of one-dimensional channels. The self-correlation function for diffusion in isotropically oriented channels is given and it is found that this function diverges at the origin. The calculations are carried out for both normal and single-file diffusion and the influence of the ballistic phase is investigated. It is found that the ballistic phase influences the scattering functions very strongly for large diffusion coefficients. QENS data from the literature are analyzed with respect to this influence. The influence of three different resolution functions (triangular, Gaussian, and Lorentzian) is considered. 相似文献
13.
In this paper, we study the effects of short channel on double gate MOSFETs. We evaluate the variation of the threshold voltage, the subthreshold slope, the leakage current and the drain-induced barrier lowering when channel length L CH decreases. Furthermore, quantum effects on the performance of DG-MOSFETs are addressed and discussed. We also study the influence of metal gate work function on the performance of nanoscale MOSFETs. We use a self-consistent Poisson-Schrödinger solver in two dimensions over the entire device. A good agreement with numerical simulation results is obtained. 相似文献
14.
Hot electron transport in silicon dioxide is examined with emphasis on current experimental and theoretical results. For oxide layers thicker than 100 Å, steady-state transport has been shown to control the carrier flow at all fields studied. The transition from a nearly thermal electron distribution at electric fields less than approximately 1.5 MV/cm to significantly hot distributions with average energies between 2 and 6 eV at higher fields of up to 16 MV/cm is discussed. The significance of nonpolar phonon scattering in controlling the dispersive transport at higher electric fields, thereby preventing runaway and avalanche breakdown, is reviewed. The transition from ballistic to steady-state transport on very thin oxides layers of less than 100 Å in thickness and the observation of single phonon scattering events are also discussed. 相似文献
15.
Jonathan Lee Anupama Yadav Michael Antia Valentina Zaffino Leonid Chernyak 《辐射效应与固体损伤》2017,172(3-4):250-256
The impact of internal irradiation with secondary Compton electrons, generated by gamma-photons, on the characteristics of III-N/GaN-based devices was explored. N-channel AlGaN/GaN high-electron-mobility transistors (HEMTs) were exposed to gamma-radiation from a 60Co source for doses up to 600?Gy. Temperature-dependent electron beam-induced current (EBIC) was employed to measure minority carrier transport properties. For low doses below ~250?Gy, the minority carrier diffusion length in AlGaN/GaN HEMTs is shown to increase by about 40%. This increase is likely due to longer minority carrier lifetime induced by internal Compton electron irradiation. An associated decrease in activation energy, extracted from temperature-dependent EBIC, was also found. The obtained increase in transconductance and decrease in gate leakage current indicate an improvement in performance of the devices after low doses of irradiation. For high doses of gamma-irradiation, above ~300?Gy, the performance of HEMTs showed a deterioration. The deterioration results from the onset of increased carrier scattering due to additional radiation-induced defects, as is translated in a decrease of minority carrier diffusion length. 相似文献
16.
F. Djeffal N. Lakhdar A. Yousfi 《Physica E: Low-dimensional Systems and Nanostructures》2011,44(1):339-344
In this paper, we have proposed and simulated a new 10-nm Dual-Material Surrounded Gate MOSFETs (DMSG) MOSFETs for nanoscale digital circuit applications. The subthreshold electrical properties such as subthreshold current–voltage characteristics, subthreshold swing factor, threshold voltage and drain induced barrier lowering (DIBL) of the device have been ascertained and mathematical models have been developed. It has been observed that the DM design can effectively suppress short-channel effects as compared to single material gate structure. The proposed analytical expressions are used to formulate the objective functions, which are the pre-requisite of genetic algorithm computation. The problem is then presented as a multi-objective optimization one where the subthreshold electrical parameters are considered simultaneously. Therefore, the proposed technique is used to search of the optimal electrical and geometrical parameters to obtain better electrical performance of the 10-nm-scale transistor. These characteristics make the optimized 10-nm transistors potentially suitable for deep nanoscale logic and memory applications. 相似文献
17.
J. Seebeck T. R. Nielsen P. Gartner F. Jahnke 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,49(2):167-170
A microscopic theory for the interaction of carriers with LO phonons
is used to study the ultrafast carrier dynamics in nitride-based
semiconductor quantum dots. It is shown that the efficiency of
scattering processes is directly linked to quasi-particle
renormalizations. The electronic states of the interacting system are
strongly modified by the combined influence of quantum confinement and
polar coupling. Inherent electrostatic fields, typical for InGaN/GaN
quantum dots, do not limit the fast scattering channels. 相似文献
18.
The two-photon-exchange (TPE) correction to elastic ep scattering in the forward angle region is discussed based on a simple hadronic model. It is found that the correction is exactly zero in the forward angle limit. This analytical result gives a good explanation of the previous numerical results and shows the clear power behavior of the TPE correction to elastic ep scattering in the forward angle region. 相似文献
19.
V. A. Kozlov V. A. Verbus A. V. Nikolaev 《Bulletin of the Russian Academy of Sciences: Physics》2007,71(1):109-112
A mechanism for achieving the terahertz negative conductivity on transmit time effects during ballistic transport of hot carriers in nanoscale semiconductor heterostructures was theoretically considered. It was shown that selection of the heterostructure potential profile can significantly increase high-frequency negative conductivity. 相似文献
20.
D. E. Sviridov V. I. Kozlovskii N. V. Zabavin 《Bulletin of the Lebedev Physics Institute》2011,38(2):41-47
Cleavages of undoped nanoscale heterostructures with GaInP/AlGaInP and CdS/ZnSSe quantum wells were studied by scanning probe microscopy. A nanorelief formed on the cleavage surface due to elastic stresses in quantum wells was detected by contact methods. The current method yielded more contrast images. It was shown that the current in undoped heterostructures depends on the Schottky barrier on the probe contact with structure layers, the intrinsic carrier concentration in them, the growth substrate doping level, the intensity and spectrum of external illumination. 相似文献