Terahertz switching action of a double-barrier resonant tunneling device

Abstract

The response of an asymmetric double barrier resonant device to the passage of terahertz radiation is discussed. Within the bistable region the radiation is able to turn the current flowing through the system on or off, with an onset that depends on the bias, the strength of the incoming radiation, and its frequency.Resonant tunneling through double-barrier structures has been the subject of much interest for their physical properties and applications as electronic devices. 1 Besides a peak due to simple resonant transmission, an intrinsic dynamical bistability and hysteresis in the negative differential resistance region of the current-voltage characteristic has been reported. [2][3][4][5][6][7] The interior of the bistability has been reached experimentally by employing a load line with positive slope, which turns the characteristic into a Z-shaped tristable curve. 8 The effect is currently understood in terms of the Coulomb repulsion experienced by the incoming electrons from the charge buildup in the space between the barriers. 3 In support of this interpretation is the fact that the width of the bistable region is enhanced by making the collector barrier wider, thus allowing for a more efficient trapping of electrons in the well. 9 A magnetic field along the device provides an additional enhancement and may introduce more complex instabilities. 5,7,10 The effect has also been detected in triple barrier structures. 11 Since the work of Sollner et al. 12 much experimental work has been devoted to the study of the effect of a timedependent potential in resonant tunneling through semiconductor microstructures. Recently Chitta et al. have studied the far-infrared response of double barrier structures. 13 There is also theoretical work reported, although most of it ignores the electron-electron interaction. We have shown recently that for an external bias near the edges of the bistable region in the I-V curve the interacting system becomes unstable under the passage of terahertz electromagnetic radiation. 14 The device can thus act as a detector of radiation in this frequency range, or as a current switch triggered by the passage of radiation. Our results were obtained by direct integration of a Schrödinger equation including a nonlinear Hartree-like term, which gave rise to numerical instabilities and the impossibility of exploring the long-term behavior of the system.In this paper we apply a rate-equation approach to the problem. Tunneling is modeled as a sequential process 15 in which the electrons are transmitted through the double barrier in steps, first from the emitter into the well, and then, from the well into the collector region. Calling k, q, and p the quantum numbers characterizing the state in the emitter, well, and collector regions, respectively, the rate equation for the occupancies f k and f q of the emitter and well states, respectively, are 15where W qk and W qp are the transmission rate from the emitter to well and from the well to the collector region, respectively. We obtain the stored charg...

Photon-assisted transport in semiconductor nanostructures

“…Furthermore, the bistability region of the unirradiated sample becomes reduced in the presence of radiation. This latter effect has been recently confirmed by Orellana et al [123].…”

Induced charge-density oscillation under a quantizing magnetic field and intense terahertz radiation

“…Many interesting terahertz phenomena have been investigated, including resonant absorption, 4 the photon enhanced hot-electron effect, 7 THz photon-induced impact ionization, 8 the LO-phonon bottleneck effect, 9 THz photon assisted tunneling, 10 THz cyclotron resonance, 11 and the Thz switching effect in resonant tunneling diodes. [12][13][14] The problem of an electron subjected simultaneously to a quantizing magnetic field and an intense terahertz laser is of particular interest due to the interplay between terahertz photons and cyclotron orbits. In the previous work, 15,16 we calculated the electronic states using unitary transformations for a free electron in a magnetic field.…”

Frequency-dependent electrical transport under intense terahertz radiation

“…Many interesting terahertz phenomena have been investigated, including resonant absorption, 3 photon enhanced hot-electron effect, 6 terahertz photon-induced impact ionization, 7 LO-phonon bottleneck effect, 8 terahertz photon assisted tunneling, 9 terahertz cyclotron resonance, 10 terahertz switching effects in tunneling diodes. [11][12][13] The conductivity changes due to an ac field radiation were calculated using a perturbative method. 14 Despite the rapid development of terahertz phenomena, a theoretical formalism describing the quantum transport in strongly coupled electron-photon systems is lacking.…”