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A traversal time that has no problem of superluminality was advanced for particles to tunnel through potential barriers in the non‐relativistic quantum theory in a previous paper by C.‐F. Li and Q. Wang, Physica B 296 (2001) 356. This time is generalized in this paper to Dirac's relativistic quantum theory. Both evanescent and propagating cases are considered. It is shown that the traversal time in the evanescent case has much the same properties as in the non‐relativistic quantum theory and thus has no problem of superluminality. It also gets rid of the problem of superluminality in the propagating case. Comparisons with the dwell time, the group delay, and the velocity of monochromatic front are also made. 相似文献
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We examine the behavior of transmission coefficient T across the rectangular barrier when attractive potential well is present on one or both sides and also the same is studied
for a smoother barrier with smooth adjacent wells having Woods-Saxon shape. We find that presence of well with suitable width
and depth can substantially alter T at energies below the barrier height leading to resonant-like structures. In a sense, this work is complementary to the resonant
tunneling of particles across two rectangular barriers, which is being studied in detail in recent years with possible applications
in mind. We interpret our results as due to resonant-like positive energy states generated by the adjacent wells. We describe
in detail the possible potential application of these results in electronic devices using n-type oxygen-doped gallium arsenide
and silicon dioxide. It is envisaged that these results will have applications in the design of tunneling devices. 相似文献
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Electron tunnelling phase time and dwell time through an associated delta potential barrier 下载免费PDF全文
The electron tunnelling phase time τP and dwell time τD through an associated delta potential barrier U(x) = ξδ(x) are calculated and both are in the order of 10^-17~10^-16s. The results show that the dependence of the phase time on the delta barrier parameter ξ can be described by the characteristic length lc = h^2/meξ and the characteristic energy Ec=meξ^2/h^2 of the delta barrier, where me is the electron mass, lc and Ec are assumed to be the effective width and height of the delta barrier with lcEc=ξ, respectively. It is found that TD reaches its maximum and τD = τp as the energy of the tunnelling electron is equal to Ec/2, i.e. as lc =λDB, λDB is de Broglie wave length of the electron. 相似文献
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Y. W. Suen C. C. Young C. J. Chang J. C. Wu S. Y. Wang C. P. Lee 《Physica E: Low-dimensional Systems and Nanostructures》2000,6(1-4)
We will present the observation of a light-induced meta-stable impurity state in a submicron center-doped double barrier tunneling diode (DBRTD) manufactured by a novel single-step e-beam lithography process in which no further alignment for the interconnect between the bonding pad and the small active device region is required. We attribute the meta-stable tunneling state, which can be switched by light and high voltage bias, to the light- or field-induced charge redistribution in the active tunneling region. 相似文献
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在有效质量近似和球形方形势模型下,计算了开放型球状纳米系统电子散射截面及电子按能量的概率分布,探讨了线度、势垒宽度对电子散射截面和共振能量以及共振宽度的影响.结果表明:电子的散射截面随能量的分布曲线有一极大值和极小值,而且电子能量的概率分布曲线的极大值位置总是介于散射截面分布曲线的极大值与极小值的能量位置之间;散射截面随内核半径r0的增大而增大,而且散射截面分布曲线随r0的增大由较平滑变得较尖锐;散射截面随势垒宽度Δ的增大而增大,但在Δ=1.4aCdS–1.7aCdS的范围内,变化出现异常,在Δ=1.6aCdS时散射截面出现极小;电子共振能量El 随Δ的变化与电子所处状态有关,而电子共振宽度Γl随Δ的增大而减小;不论Δ取何值, El和Γl都满足能量和时间的测不准关系.
关键词:
球状纳米系统
势垒宽度
电子散射截面
电子概率分布 相似文献
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In this paper, we obtain reliable expressions to calculate the barrier and pocket positions of the real part of the effective
phenomenological optical potential having Woods-Saxon form factor, for different partial waves. The comparison of the results
obtained from these formulae, when compared with the numerical results obtained using Newton-Raphson iterative procedure are
found to be quite accurate, with error less than 1%. We also obtain algebraic expressions for estimatingl
poc, the angular momentum at which the potential pocket vanishes, the accuracy of which is tested with the exact calculations,
using self-consistent iterative procedures. These and other expressions deduced in this paper provide simple and useful methods
for calculating critical parameters of heavy ion effective potentials like barrier and pocket positions, curvatures at the
barrier and pocket positions,l
poc and the grazing angular momentuml
g to carry out the analysis of heavy ion scattering. 相似文献
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用Heaviside函数构造出一维对称的Hulthén势垒,求解了其满足的Klein-Gordon方程. 散射态的精确解可以由超几何函数表示, 透射系数T和反射系数R能由Klein-Gordon 方程满足的边界条件得到.并由流密度守恒推导出低动量粒子发生透射共振的条件.
关键词:
Klein-Gordon方程
Hulthén势垒
散射态
透射共振 相似文献
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Vittoria Petrillo Giorgia Alberti Luca Celardo Francesco Cerutti Silvano Franchi Vittorio Mariani 《Central European Journal of Physics》2006,4(2):196-209
The effect of a position measurement on one component of a two-particle wave packet in a regularized space-momentum entangled
state is analyzed. The wave packet interacts in the physical space with a potential barrier. When a position or momentum measurement
is performed on one particle, a consequent strong modification of the dynamics of the other particle occurs. 相似文献
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Mehmet Batı 《Chinese Journal of Physics (Taipei)》2018,56(2):593-597
We study resonant tunneling characteristics of inverted Morse double quantum barrier structures. The effect of electric bias and structure parameters is calculated by using non-equilibrium Green's function method. Results for the transmission coefficients are compared with the structure parameters. Our results show that the widths of the wells and heights of barriers have a significant effect on the transmission properties. We found that the resonant peak of the transmission coefficient decreases with increasing electric field bias. Moreover, resonant energy level increases with increasing barrier height and increasing width parameters. 相似文献
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As is known to all, the electron scattering in classical electromagnetic potential is one of the most widespread applications of quantum theory. Nevertheless, many discussions about electron scattering are based upon single-particle Schrodinger equation or Dirac equation in quantum mechanics rather than the method of quantum field theory. In this paper, by using the path integral approach of quantum field theory, we perturbatively evaluate the scattering amplitude up to the second order for the electron scattering by the classical electromagnetic potential. The results we derive are convenient to apply to all sorts of potential forms. Furthermore, by means of the obtained results, we give explicit calculations for the one-dimensional electric potential. 相似文献
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Bifurcation of a periodic instanton and quantum-classical transition in the biaxial nano-ferromagnet with a magnetic field along hard axis 下载免费PDF全文
Crossover from classical to quantum regimes of the barrier transition rate in a biaxial ferromagnetic magnet with a magnetic field applied along hard anisotropy axis is investigated. We show that the type of action-temperature diagrams can he determined by counting the number of bifurcation points. The model possesses not only the known type I and Ⅱ, hut also the interesting type Ⅲ and Ⅳ of transition which do not occur in general. 相似文献
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《Current Applied Physics》2015,15(11):1421-1427
The effect of negative electric field on spin-dependent tunneling in double barrier heterostructures of III–V semiconductor is theoretically investigated. The transfer matrix approach is used by considering Dresselhaus and induced-Rashba effect to calculate the barrier transparency and polarization efficiency. Cent percent polarization efficiency can be achieved for the negative electric field by increasing the width of the potential barrier. The separation between spin-up and spin-down resonances are evaluated. The separation between spin resonances and tunneling lifetime of electrons are observed for various negative electric fields as well as for various barrier widths. The linear variation of spin separation and tunneling lifetime of electrons are observed as a function of negative electric field. 相似文献
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In this paper, a novel structure for quantum ring inter-subband photodetectors (QRIP) is proposed to reduce its dark current. Some additional layers including asymmetric multi-barrier resonant tunneling (AMBRT) in absorption region layers are exploited to provide near unity tunneling probability for generated photocurrents and completely reject thermally generated electrons. AMBRT structure consists of three asymmetric AlGaAs barriers and two InGaAs wells which are designed for operation wavelength of generated photocurrents by absorption of 20 μm. Simulation results show that AMBRT can considerably reduce the dark current compared to previously proposed resonant tunneling structure about three orders of magnitude. As a consequent, higher specific detectivity for AMBRT-QRIP is obtained in the order of ∼1011 cm Hz1/2/W at 100 K. 相似文献
17.
This paper studies the electronic transport property
through a square potential barrier in armchair-edge graphene
nanoribbon (AGNR). Using the Dirac equation with the continuity
condition for wave functions at the interfaces between regions with
and without a barrier, we calculate the mode-dependent transmission
probability for both semiconducting and metallic AGNRs,
respectively. It is shown that, by some numerical examples, the
transmission probability is generally an oscillating function of the
height and range of the barrier for both types of AGNRs. The main
difference between the two types of systems is that the magnitude of
oscillation for the semiconducting AGNR is larger than that for
the metallic one. This fact implies that the electronic transport
property for AGNRs depends sensitively on their widths and edge
details due to the Dirac nature of fermions in the system. 相似文献
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Resonant tunneling quantum structures consist of asymmetric wells and barriers have been investigated to find their optimized geometrical parameters and potential profile by the numerical calculations. The results show that the widths and the depths of the asymmetric wells have a significant effect on the transmission coefficient and the dwell time. The properties exhibited in this work may establish guidance to the device applications. 相似文献
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分析电子隧穿简单势垒所产生的电子-空穴对的纠缠特性.基于能级配置的差异,协力纠缠度(concurrence)随势垒高度变化呈规律性的变化特征. 相似文献