Population inversion in optically pumped asymmetric quantum well terahertz lasers

Harrison, P.; Kelsall, R. W.

doi:10.1063/1.365310

Cited by 44 publications

(25 citation statements)

References 19 publications

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“…The structures prepared in such a way seem to be very attractive for fabrication of the THz detectors and emitters. [5][6][7] In this respect, the Be ␦-doped GaAs/ AlAs multiple quantum well ͑MQW͒ system is of special interest as it gives the maximum possible confinement for the acceptor states in the valence band and, thus, the maximum possible tuning range for the dipoleallowed 1s-2p transition of the acceptor. Usually, such intraacceptor transitions are studied at low doping densities ͑Ͻ3 ϫ 10 16 cm −3 ͒ to avoid impurity band effects smearing out the sharp absorption lines at higher concentrations.…”

Section: Introductionmentioning

confidence: 99%

Photoreflectance and surface photovoltage spectroscopy of beryllium-doped GaAs∕AlAs multiple quantum wells

Čechavičius¹,

Kavaliauskas²,

Krivaitė

et al. 2005

Journal of Applied Physics

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Article:Cechavicius, B., Kavaliauskas, J., Krivaite, G. et We present an optical study of beryllium ␦-doped GaAs/ AlAs multiple quantum well ͑QW͒ structures designed for sensing terahertz ͑THz͒ radiation. Photoreflectance ͑PR͒, surface photovoltage ͑SPV͒, and wavelength-modulated differential surface photovoltage ͑DSPV͒ spectra were measured in the structures with QW widths ranging from 3 to 20 nm and doping densities from 2 ϫ 10 10 to 5 ϫ 10 12 cm −2 at room temperature. The PR spectra displayed Franz-Keldysh oscillations which enabled an estimation of the electric-field strength of ϳ20 kV/ cm at the sample surface. By analyzing the SPV spectra we have determined that a buried interface rather than the sample surface mainly governs the SPV effect. The DSPV spectra revealed sharp features associated with excitonic interband transitions which energies were found to be in a good agreement with those calculated including the nonparabolicity of the energy bands. The dependence of the exciton linewidth broadening on the well width and the quantum index has shown that an average half monolayer well width fluctuations is mostly predominant broadening mechanism for QWs thinner than 10 nm. The line broadening in lightly doped QWs, thicker than 10 nm, was found to arise from thermal broadening with the contribution from Stark broadening due to random electric fields of the ionized impurities in the structures. We finally consider the possible influence of strong internal electric fields, QW imperfections, and doping level on the operation of THz sensors fabricated using the studied structures.

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Section: Introductionmentioning

confidence: 99%

Photoreflectance and surface photovoltage spectroscopy of beryllium-doped GaAs∕AlAs multiple quantum wells

Čechavičius¹,

Kavaliauskas²,

Krivaitė

et al. 2005

Journal of Applied Physics

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“…[1][2][3][4][5] Confinement of such impurities in quasi-two-dimensional GaAs/Al x Ga 1Ϫx As quantum wells ͑QWs͒ allows the tuning of these levels in a controlled way. For device applications the greater range the binding energy of the impurity can be tuned over the better.…”

Section: Introductionmentioning

confidence: 99%

Acceptor binding energy in δ-doped GaAs/AlAs multiple-quantum wells

Zheng

Halsall

Harmer

et al. 2002

Journal of Applied Physics

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ArticleA series of Be ␦-doped GaAs/AlAs multiple-quantum wells with the doping at the well center were grown by molecular beam epitaxy. The photoluminescence spectra were measured at 4, 20, 40, 80, 120, and 200 K, respectively. The two-hole transitions of the acceptor-bound exciton from the ground state, 1S 3/2 (⌫ 6 ), to the first-excited state, 2S 3/2 (⌫ 6 ), have been clearly observed and the acceptor binding energy measured. A variational calculation is presented to obtain the acceptor binding energy as a function of well width. It is found that the experimental results are in good agreement with the theory.

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“…Studies of the internal transition of quantum confined shallow impurities are currently attracting a great deal of attention for the physical phenomena they exhibit and their potential for a range of opto-electronic applications, such as far-infrared detectors and a solid state Terahertz laser [1][2][3][4] . Confinement of such impurities in quasi-two-dimensional GaAs/Al x Ga 1−x As quantum wells allows the tuning of their levels in a controlled way.…”

Section: Introductionmentioning

confidence: 99%

Far-infrared absorption studies of Be acceptors in δ-doped GaAs/AlAs multiple quantum wells

et al. 2006

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We report a far-infrared absorption study of internal transitions of shallow Be acceptors in both bulk GaAs and a series of δ-doped GaAs/AlAs multiple quantum well samples with well thicknesses of 20, 15 and 10 nm. Low temperature far-infrared absorption measurements clearly show three principal absorption lines due to transitions of Beacceptor states from the ground state to the first three odd-parity excited states, respectively. Using a variational principle, the 2p-1s transition energies of quantum confined Be acceptors are calculated as a function of the well width. It is found that the theoretical calculation of the 2p z → 1s transitions is in good agreement with the D-like line experimental data.

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Population inversion in optically pumped asymmetric quantum well terahertz lasers

Cited by 44 publications

References 19 publications

Photoreflectance and surface photovoltage spectroscopy of beryllium-doped GaAs∕AlAs multiple quantum wells

Photoreflectance and surface photovoltage spectroscopy of beryllium-doped GaAs∕AlAs multiple quantum wells

Acceptor binding energy in δ-doped GaAs/AlAs multiple-quantum wells

Far-infrared absorption studies of Be acceptors in δ-doped GaAs/AlAs multiple quantum wells

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