Resonant tunneling spectroscopy of two coupled quantum wells

Zohta, Yasuhito; Nozu, T.; Obara, M.

doi:10.1103/physrevb.39.1375

Cited by 12 publications

(8 citation statements)

References 17 publications

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“…The first evidence of tunnelling between two purely 2D systems separated by a single barrier was reported in the late 1980s [102]. The early work of Zohta et al [32], for a triple-barrier system, demonstrated the significance of tailoring a barrier that would separate electrons in two different quantum wells. Interesting I -V characteristics were observed in that work [32] including NDR properties and high peak to valley ratios.…”

Section: Application To the Triple-barrier (Double Well) Systemmentioning

confidence: 99%

“…Depending on the thickness of the middle barrier the system's eigenstates depend on the wavefunction overlap between the two wells. In fact, the first observation of the energy splitting obtained in a triple-barrier system, with a thin middle barrier, was reported over a decade ago [32] using resonant tunnelling spectroscopy [5,23]. The interest in this more recent class of quantum wells is due to the ability to tailor the middle barrier and permit the investigation of quantum phenomena [32], including electron-electron interactions [33] and the Coulomb gap [34].…”

Section: Introductionmentioning

confidence: 99%

“…In fact, the first observation of the energy splitting obtained in a triple-barrier system, with a thin middle barrier, was reported over a decade ago [32] using resonant tunnelling spectroscopy [5,23]. The interest in this more recent class of quantum wells is due to the ability to tailor the middle barrier and permit the investigation of quantum phenomena [32], including electron-electron interactions [33] and the Coulomb gap [34]. Furthermore, in order to improve the ability to control the tunnelling process and thereby create transistor action, the third layer, i.e.…”

Section: Introductionmentioning

confidence: 99%

“…It should be noted that, while double quantum well systems come in triple [32] or single [35] barriers, for example, in this review no rigorous distinction will be addressed between them due to their similarity. As far as this review is concerned the difference in their electronic behaviour is an open question.…”

Section: Introductionmentioning

confidence: 99%

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Conductance in double quantum well systems

Hasbun

2003

J. Phys.: Condens. Matter

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The object of this paper is to review the electronic conductance in double quantum well systems. These are quantum well structures in which electrons are confined in the z direction by large band gap material barrier layers, yet form a free two-dimensional Fermi gas within the sandwiched low band gap material layers in the x–y plane. Aspects related to the conductance in addition to the research progress made since the inception of such systems are included. While the review focuses on the tunnelling conductance properties of double quantum well devices, the longitudinal conductance is also discussed. Double quantum well systems are a more recent generation of structures whose precursors are the well known double-barrier resonant tunnelling systems. Thus, they have electronic signatures such as negative differential resistance, in addition to resonant tunnelling, whose behaviours depend on the wavefunction coupling between the quantum wells. As such, the barrier which separates the quantum wells can be tailored in order to provide better control of the device’s electronic properties over their single well ancestors.

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Section: Application To the Triple-barrier (Double Well) Systemmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Conductance in double quantum well systems

Hasbun

2003

J. Phys.: Condens. Matter

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“…4,15,16 Here we propose to use magnetic resonant tunneling diodes ͑RTDs͒ comprising coupled magnetic QWs and three nonmagnetic barriers, as spintronic devices offering large magnetocurrents ͑MCs͒. Corresponding nonmagnetic three barrier structures have been experimentally studied, [17][18][19][20] while electric field domain formation in magnetic multiple QWs was theoretically investigated in Ref. 21.…”

mentioning

confidence: 99%

Resonant tunneling magnetoresistance in coupled quantum wells

Ertler

Fabian

2006

Applied Physics Letters

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A three barrier resonant tunneling structure in which the two quantum wells are formed by a magnetic semiconductor is theoretically investigated. Self-consistent numerical simulations of the structure predict giant magnetocurrent in the resonant bias regime as well as significant current spin polarization for a considerable range of applied biases. The requirements for large magnetocurrent are spin resolved resonance levels as well as asymmetry ͑spatial or magnetic͒ of the coupled quantum wells. © 2006 American Institute of Physics. ͓DOI: 10.1063/1.2402878͔Semiconductor spintronics offers additional functionalities to the existing electronics technology by combining charge and spin properties of the current carriers. 1 Spin dependent resonant tunneling in double barrier heterostructures has been investigated both experimentally and theoretically with a magnetic quantum well ͑QW͒ made of semimetallic ErAs ͑Refs. 2 and 3͒ or dilute magnetic semiconductors ͑DMSs͒ such as GaMnAs ͑Refs. 4-9͒ or ZnMnSe ͑Refs. 10 and 11͒. Such diodes have been used as spin filters or spin detectors and effective injection of spin-polarized electrons into semiconductors has been demonstrated by employing interband tunneling devices based on GaMnSb. 12,13 A theoretical investigation of resonant tunneling through a nonmagnetic double barrier structure, e.g., AlAs/ GaAs/ AlAs, sandwiched between two bulk ferromagnetic DMSs, e.g., GaMnAs, shows a tremendous enhancement of the tunneling magnetoresistance ͑TMR͒ for low voltages if the thickness of the QW is properly tuned. 14 The effect has been demonstrated to be as high as 10 000% for generic parabolic bands and when including a more realistic kp band structure model still very high TMRs of about 800% have been obtained. 14 Such structures have already been grown and studied experimentally. 4,15,16 Here we propose to use magnetic resonant tunneling diodes ͑RTDs͒ comprising coupled magnetic QWs and three nonmagnetic barriers, as spintronic devices offering large magnetocurrents ͑MCs͒. Corresponding nonmagnetic three barrier structures have been experimentally studied, [17][18][19][20] while electric field domain formation in magnetic multiple QWs was theoretically investigated in Ref. 21. The magnetic three barrier structure allows to establish parallel ͑P͒ and antiparallel ͑AP͒ magnetization configurations and to observe MC. The QWs are assumed to be made of ferromagnetic semiconductors. 5,22 We consider here generic parabolic n-type ferromagnetic QWs, though one expects to observe similar effects in coupled p-type ferromagnetic QWs. Several suitable n-type ferromagnetic semiconductors have been reported: 1 HgCr 2 Se 4 , 23 CdCr 2 Se 4 , 24 CdMnGeP 2 , 25 or most promising ZnO and GaMnN; 22,27 the latter two are believed to exhibit room temperature ͑RT͒ ferromagnetism. To be specific we perform our numerical simulations for GaMnNbased structures.However, it is still controversial if the reported RT ferromagnetism in transition metal doped GaN and ZnO is due to non-resolved precipitates or n...

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