Optical properties of stepped InxGa1−xAs/GaAs quantum wells

D’Andrea, Andrea; Tomassini, N.; Ferrari, L.; Righini, M.; Selci, S.; Bruni, M. R.; Schiumarini, D.; Simeone, M.G.

doi:10.1063/1.367971

Cited by 16 publications

(7 citation statements)

References 19 publications

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“…[2] Previous investigations on the optical properties of In-GaAs±GaAs strained symmetric quantum wells (SQW) have provided considerable evidence on the high quality achievable in samples grown with this type of semiconductor alloy material. [9] These results indicate that our samples are adequately described by a theoretical model that assumes an abrupt confinement potential and a homogeneous, yet strained, InGaAs alloy composition in each layer. In this study we concentrate on the power and temporal dependence of the AQW PL to illustrate a phenomenology consistent with exciton localization at the alloy±alloy interface.…”

supporting

confidence: 58%

“…This finding is in agreement with the reported sublinear power dependence. [9,16,17] This fact, together with the confirmation of the In-alloy homogeneity composition and of the potential-profile sharpness given by the R and HRXRD results, points at the In x Ga 1±x As± In y Ga 1±Iy As interface as the primary source of the AQW PL behaviour. Fig.…”

Section: Communicationsmentioning

confidence: 85%

“…The agreement is slightly worse for the excited heavy-hole transition (labeled hh 3 -e 1 ). [9] It is noticeable that the PL lineshape is very sensitive to small variations in the excitation power density, i.e., powers remain within one order of magnitude. Nevertheless, all reported differences are within those usually observed in similar strained InGaAs±GaAs SQW's.…”

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confidence: 99%

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Spectroscopic Signatures of the Alloy-Alloy Interface in InGaAs-GaAs(001) Stepped Quantum Wells: a Frequency- and Time-Resolved Study

et al. 2002

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Semiconductor heterostructures based on different compositions of the same alloy are important for the realization of new electronic and photonic devices. Stepped quantum wells are considered as good candidates for the enhancement of non-linear optical properties. [1] There have been, however, very few studies devoted to the properties of the alloy±alloy interface common to all these materials. [2] Previous investigations on the optical properties of In-GaAs±GaAs strained symmetric quantum wells (SQW) have provided considerable evidence on the high quality achievable in samples grown with this type of semiconductor alloy material. [3±5] On the contrary, we observe that while stepped± asymmetric quantum well (AQW) reflectivity (R) spectra agree well with theory, photoluminescence (PL) spectra show a somewhat peculiar behavior. In this study we concentrate on the power and temporal dependence of the AQW PL to illustrate a phenomenology consistent with exciton localization at the alloy±alloy interface.Three AQW samples were grown on a GaAs(001) substrate by molecular beam epitaxy (MBE) techniques in a computercontrolled Varian GEN II machine. They consist of a double layer of In x Ga 1-x As/In y Ga 1-y As alloy (x = 0.064, y = 0.149) of equal thickness (L x = L y = 3.2, 4.2, and 5.2 nm for samples SS22, SS23, and SS24 respectively). Growth interruption was implemented between the growth of the GaAs substrate and InGaAs alloy to minimize defect formation at the interface. Uninterrupted growth of the ternary alloy layers was achieved by the use of two indium furnaces at T 1 = 596 C and T 2 = 696 C. Sample monitoring and characterization was performed in situ by means of reflection high-energy electron diffraction (RHEED) and ex situ by high-resolution X-ray diffraction (HRXRD). The HRXRD rocking curves were compared with simulated spectra and were found to be consistent with a homogeneous composition of barriers and wells, as well as with sharp discontinuities at the interfaces.Reflectivity (R) spectra were recorded at temperatures ranging between 10±300 K using a spectrometer as described in ref. 6. Excitonic properties were calculated using a parameter-free exciton model within the effective-mass approximation which explicitly takes into account the following effects:(1) valence band degeneracy; (2) hydrostatic and uniaxial strain owing to the large lattice mismatch between GaAs (a o = 0.565 nm) and InGaAs alloys (a o = 0.606 nm for InAs);(3) finite confinement potentials for electrons and holes; (4) image potentials; and (5) quasi-continuum states outside the well potentials. [7] The theoretical optical response was computed by numerically solving Maxwell's equations taking into account spatial dispersion effects. [8] The calculations have assumed an abrupt potential energy profile along the well.The experimental and theoretical AQW reflectivity peak positions are shown in Table 1. The agreement is very good for the excitonic ground state transitions. For sample SS22, the discrepancy is as low as 0.8 meV, and for ...

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Section: Communicationsmentioning

confidence: 85%

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confidence: 99%

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Spectroscopic Signatures of the Alloy-Alloy Interface in InGaAs-GaAs(001) Stepped Quantum Wells: a Frequency- and Time-Resolved Study

et al. 2002

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“…For the case of isolated resonant lines, Lorentz approximation was applied to extract val- Table I. Dashed line in (a) is the theoretically calculated oscillator strength taken from [6]. Dash-dotted line in (b) is averaged value of measured Γ0 (70 µeV).…”

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confidence: 99%

“…For the (Al,Ga)As/GaAs SQW structures, where heavy-hole exciton wave-function is highly confined within the well layer, the exciton oscillator strength is higher for smaller well thicknesses [3][4][5], although inhomogeneity for narrower quantum wells is higher too. Excitons in (In,Ga)As/GaAs SQW reveal tendency to a reduction of oscillator strength with decreasing well thickness [6,7], because the exciton wavefunction easily penetrates the barriers and confinementenhanced Coulomb interaction between electron and hole reduces. For both systems, the reported linewidths of heavy-hole exciton resonance are always a few times broader as compared to the radiative linewidth [7,8], which is of the order of 60 µeV [9].…”

Section: Introductionmentioning

confidence: 99%

Extremely low inhomogeneous broadening of exciton lines in shallow (In,Ga)As/GaAs quantum wells

Poltavtsev

Efimov

Dolgikh

et al. 2014

Solid State Communications

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We study radiative linewidth of exciton resonance in shallow InxGa1−xAs/GaAs single quantum wells as a function of indium concentration in the range x = 0.02...0.10 and well thickness in the range LZ = 1...30 nm using the method of Brewster reflection spectroscopy. Record linewidths of heavyhole exciton resonance of about 130...180 µeV are measured in reflection spectra for single quantum wells with LZ = 2 nm and x = 0.02 at temperature 9 K. In these spectra, the non-radiative linewidth including inhomogeneous broadening can be comparable or even less than radiative linewidth. It is shown that radiative linewidth weakly depends on x and LZ in these ranges. In multiple-quantumwell Bragg structure with ten periods radiative linewidth exceeds inhomogeneous broadening by 4 times.

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Energy spectrum of excitons in square quantum wells

Belov

2019

Physica E: Low-dimensional Systems and Nanostructures

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Optical properties of stepped InxGa1−xAs/GaAs quantum wells

Cited by 16 publications

References 19 publications

Spectroscopic Signatures of the Alloy-Alloy Interface in InGaAs-GaAs(001) Stepped Quantum Wells: a Frequency- and Time-Resolved Study

Spectroscopic Signatures of the Alloy-Alloy Interface in InGaAs-GaAs(001) Stepped Quantum Wells: a Frequency- and Time-Resolved Study

Extremely low inhomogeneous broadening of exciton lines in shallow (In,Ga)As/GaAs quantum wells

Energy spectrum of excitons in square quantum wells

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