Bound-free intraband absorption in GaAs-Al<i>x</i>Ga1−<i>x</i>As semiconductor quantum wells

Ikonić, Z.; Milanović, V.; Tjapkin, D.

doi:10.1063/1.100979

Cited by 42 publications

(10 citation statements)

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“…To treat the energy eigenstates above the barrier, the MQW structure was embedded between infinitely large barriers carriers at sufficiently large distances such that the far distance boundary conditions do not affect the calculated absorption spectra. 6 To measure the photocurrent spectrum, circular devices with 200 m diameter were defined by wet chemical etching. AuGe/Ni/Au was deposited onto the top and bottom n ϩ -GaAs contact layers.…”

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confidence: 99%

Quantum interference effect and electric field domain formation in quantum well infrared photodetectors

Shakouri

Yariv

1995

Applied Physics Letters

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An observation of quantum interference effect in photocurrent spectra of a weakly coupled bound-to-continuum multiple quantum well photodetector is reported. This effect persists even at high biases where the Kronig-Penney minibands of periodic superlattice potential in the continuum are destroyed. Our results show that electrons remain coherent over a distance of 40-50 nm. The observation was used to investigate electric field domain formation induced by sequential resonant tunneling in the superlattice. A large off-resonant energy level alignment between two neighboring wells in the high field domain was observed. © 1995 American Institute of Physics.Recently, there has been great interest in studying optical and transport properties of multiple quantum well ͑MQW͒ structures. In these ''artificial molecules,'' energy quantization and wave nature of carriers have been used to design new devices and to demonstrate some basic laws of quantum mechanics, e.g., to observe minibands in the continuum of periodic potential superlattice, 1 to observe suppression of optical absorption in coupled potential wells, 2 and to make quantum well infrared photodetectors ͑QWIPs͒ by using minibands in the continuum.3 In this letter, we report on a new observation of a quantum interference effect in the photocurrent spectra in bound-to-continuum QWIPs. Using this effect, we analyze the electric field domain formation in the superlattice.In a weakly coupled MQW structure with two bound states in each well ͑i.e., a bound-to-bound QWIP͒, 3 the absorption spectrum is a Lorentzian shape peak corresponding to a transition between the ground state and the first excited state. The contribution of other states in the continuum above the barrier is negligible because of the oscillator strength sum rule ͑one-to-two transition, both states being localized in the well, has a much more significant transition dipole matrix element͒.When the quantum well parameters allow only one state in the well ͑i.e., a bound-to-continuum QWIP͒, the absorption spectrum is not Lorentzian any more, the states above the barriers have a strong contribution to the absorption. Because these continuum states are extended over the barriers and several neighboring wells ͑depending on the coherence length of electrons͒, electron interference effects can be observed in the absorption spectrum. At zero bias, due to the potential translation symmetry there are well-known minibands in the continuum states of the superlattice 1 which can be calculated using, for example, the Kronig-Penney model. The miniband energy gaps, depending on the overlap of the states between neighboring wells, can be designed large enough to be observable in the absorption spectrum. However, under an applied bias, such that the voltage drop per period is bigger than these energy gaps, the miniband structure is destroyed. We will show that in a QWIP even at large biases, one can still see some features in the photocurrent spectrum which are due to electron interference effects over one or two periods ...

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Quantum interference effect and electric field domain formation in quantum well infrared photodetectors

Shakouri

Yariv

1995

Applied Physics Letters

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“…3 shows the photocurrent curve for the bias voltage at 1.0 V together with the two deconvoluted Lorentzian peaks ͑dotted lines͒ and the fitted curve ͑dashed lines͒. 11 In spite of the structural asymmetry, the state-of-the-art Stranski-Krastanov QDs have a small height/ width ratio ͑about 1:7 in our case͒. Given all the facts mentioned above, we can then explore the origin of the two peaks.…”

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confidence: 93%

Voltage tunable two-color InAs∕GaAs quantum dot infrared photodetector

Yang

Chong

et al. 2008

Applied Physics Letters

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We report a bias voltage tunable two-color InAs∕GaAs quantum dot infrared photodetector working under the normal incidence infared irradiation. The two-color detection of our device is realized by combining a photovoltaic and a photoconductive response by bias voltage tuning. The photovoltaic response is attributed to the transition of electron from the ground state to a high continuum state. The photoconductive response arises from the transition of electron from the ground state to the wetting layer state through the barrier via Fowler–Nordheim tunneling evidenced by a broad feature of the photocurrent peak on the high energy side.

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“…[1][2][3][4][5][6][7][8] Relatively few discussions are dedicated to the absorption due to bound-to-continuum transitions in quantum wells. Ikonic et al 9 have investigated the bound-tocontinuum transitions in quantum wells without the electric field. Using the electric field to modulate the absorption spectrum due to bound-to-continuum transitions is of importance from both the scientific and technological point of view.…”

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confidence: 99%

Intersubband electroabsorption spectra of semiconductor quantum wells

Kuo

Chang

2000

Journal of Applied Physics

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The electroabsorption spectra of semiconductor quantum wells due to intersubband (including bound to continuum) transitions are studied theoretically within the effective-mass model. Interesting oscillatory behavior in the absorption spectra due to the Franz–Keldysh effect is explored. The calculated absorption spectra due to the electric field modulation are found in good agreement with available experimental data.

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Bound-free intraband absorption in GaAs-AlxGa1−xAs semiconductor quantum wells

Cited by 42 publications

References 3 publications

Quantum interference effect and electric field domain formation in quantum well infrared photodetectors

Quantum interference effect and electric field domain formation in quantum well infrared photodetectors

Voltage tunable two-color InAs∕GaAs quantum dot infrared photodetector

Intersubband electroabsorption spectra of semiconductor quantum wells

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