Coulomb-driven terahertz-frequency intrinsic current oscillations in a double-barrier tunneling structure

Jonasson, Olafur; Knežević, I.

doi:10.1103/physrevb.90.165415

Cited by 18 publications

(15 citation statements)

References 45 publications

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“…13 Electron densities n(z, x, t) at different times scheme with respect to the -direction as described in [24] is adopted. THz oscillations of the current density are observed as previously described by [45][46][47].…”

Section: Resonant Algaas/gaas Tunneling Diodementioning

confidence: 65%

Subdomain-based exponential integrators for quantum Liouville-type equations

2021

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In order to describe quantum mechanical effects, the use of the von-Neumann equation is apparent. In this work, we present a unified numerical framework so that the von-Neumann equation in center-of-mass coordinates leads to a Quantum Liouville-type equation when choosing a suitable basis. In particular, the proposed approach can be related to the conventional Wigner equation when a plane wave basis is used. The drawback of the numerical methods is the high computational cost. Our presented approach is extended to allow reducing the dimension of the basis, which leads to a computationally efficient and accurate subdomain approach. Not only the steady-state behavior is of interest, but also the dynamic behavior. In order to solve the time-dependent case, suitable approximation methods for the time-dependent exponential integrator are necessary. For this purpose, we also investigate approximations of the exponential integrator based on Faber polynomials and Krylov methods. In order to evaluate and justify our approach, various test cases, including a resonant tunnel diode as well as a double-gate field-effect transistor, are investigated and validated for the stationary and the dynamic device behavior.

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Section: Resonant Algaas/gaas Tunneling Diodementioning

confidence: 65%

Subdomain-based exponential integrators for quantum Liouville-type equations

2021

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“…We discuss why in some circumstances the use of the Boltzmann collision operator can produce unphysical results. It is important to notice here that the Boltzmann collision operator is usually implemented through the use of the Fermi Golden rule that determines the scattering rates 5 [3,25,31]. In our work, we do not discuss the range of validity of the approximation of the Fermi Golden rule, but only some inherent difficulties that can be found in the practical implementation of the Boltzmann collision operator in quantum simulators.…”

Section: The Wigner Distribution Function Formalismmentioning

confidence: 99%

Unphysical features in the application of the Boltzmann collision operator in the time-dependent modeling of quantum transport

Zhan¹,

Colomés²,

Oriols³

2016

J Comput Electron

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In this work, the use of the Boltzmann collision operator for dissipative quantum transport is analyzed. Its mathematical role on the description of the time-evolution of the density matrix during a collision can be understood as processes of adding and subtracting states. We show that unphysical results can be present in quantum simulations when the old states (that built the density matrix associated to an open system before the collision) are different from the additional states generated by the Boltzmann collision operator. As a consequence of the Fermi Golden rule, the new generated sates are usually eigenstates of the momentum or kinetic energy. Then, the different time-evolutions of old and new states involved in a collision process can originate negative values of the charge density, even longer after the collision. This unphysical feature disappears when the Boltzmann collision operator generates states that were already present in the density matrix of the quantum system before the collision. Following these ideas, in this paper, we introduce an algorithm that models phonon-electron interactions through the Boltzmann collision operator without negative values of the charge density. The model only requires the exact knowledge, at all times, of the states that build the density matrix of the open system.

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“…In the derivation of this formula,

is phenomenologically introduced by assuming that electrons are affected only by the time delay

at resonant tunneling [ 65 ]. A detailed analysis for a more exact treatment is a future subject, including, for example, the potential change due to electron accumulation in the well [ 67 , 68 ], photon-assisted tunneling [ 69 , 70 , 71 ], and so on, or more precise quantum-mechanical analyses [ 72 , 73 , 74 ]. In fact, the experimental result of the frequency dependence of

[ 52 ] slightly deviated from the above formula, although more experimental data are needed.…”

Section: Structure Oscillation Principle and Oscillation Charactmentioning

confidence: 99%

Terahertz Emitter Using Resonant-Tunneling Diode and Applications

Asada

Suzuki

2021

Sensors

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A compact source is important for various applications utilizing terahertz (THz) waves. In this paper, the recent progress in resonant-tunneling diode (RTD) THz oscillators, which are compact semiconductor THz sources, is reviewed, including principles and characteristics of oscillation, studies addressing high-frequency and high output power, a structure which can easily be fabricated, frequency tuning, spectral narrowing, different polarizations, and select applications. At present, fundamental oscillation up to 1.98 THz and output power of 0.7 mW at 1 THz by a large-scale array have been reported. For high-frequency and high output power, structures integrated with cylindrical and rectangular cavities have been proposed. Using oscillators integrated with varactor diodes and their arrays, wide electrical tuning of 400–900 GHz has been demonstrated. For spectral narrowing, a line width as narrow as 1 Hz has been obtained, through use of a phase-locked loop system with a frequency-tunable oscillator. Basic research for various applications—including imaging, spectroscopy, high-capacity wireless communication, and radar systems—of RTD oscillators has been carried out. Some recent results relating to these applications are discussed.

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Coulomb-driven terahertz-frequency intrinsic current oscillations in a double-barrier tunneling structure

Cited by 18 publications

References 45 publications

Subdomain-based exponential integrators for quantum Liouville-type equations

Subdomain-based exponential integrators for quantum Liouville-type equations

Unphysical features in the application of the Boltzmann collision operator in the time-dependent modeling of quantum transport

Terahertz Emitter Using Resonant-Tunneling Diode and Applications

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