# Effects of a Gaussian size distribution on the absorption spectra of III-V semiconductor quantum dots

TL;DR: In this paper, the absorption spectra of realistic QD systems with dot size distribution described by a Gaussian function were formulated and compared with ideal dot having infinite potentials at the boundaries.

Abstract: The advancement in the fabrication of low-dimensional semiconductor structures has made it possible to grow zero-dimensional electron-hole systems called quantum dots (QDs). In recent years, there have been extensive studies on III-V semiconductor QDs. In this paper, we have formulated the absorption spectra of realistic QD systems with dot size distribution described by a Gaussian function. The dots were approximated as cubic boxes having finite potentials at the boundaries. The effects of size nonuniformity on the optical absorption spectra of few realistic QD systems were analyzed, and the results have been compared with ideal dots having infinite potentials at the boundaries.

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TL;DR: In this article, the intersublevel absorption peak energy and absorption coefficient of non-uniform quantum dot ensembles are calculated analytically and the effect of size variations and size distribution of QDs on their energy states is analyzed.

Abstract: The intersublevel absorption peak energy and absorption coefficient of non-uniform quantum dot (QD) ensembles are calculated analytically. The effect of size variations and size distribution of QDs on their energy states is analyzed. The dots are considered as a quantum box with finite potential at the barriers and the size distribution described by a Gaussian function. The influence of the aspect ratio (base to height ratio) of the QDs on the optical transitions is studied. Our model predicts the dot size (height and base) accurately to determine the absorption peaks and corresponding absorption coefficient. We also compute the absorption coefficient of the QD with different size distributions to verify the results calculated using this model with the reported experimental and other theoretical results.

22 citations

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TL;DR: In this paper, the density of optical transitions, absorption, and differential absorption spectra of quantum dot ensembles is modeled using a Gaussian-peak model with a preside account of the influence of size dispersion on the line shape of quantum dots.

Abstract: We propose a method to model the density of optical transitions, absorption, and differential-absorption spectra of quantum dot ensembles. The developed approach combines physical straightforwardness of the conventional Gaussian-peak modeling with a more preside account of the influence of size dispersion on the line shape of quantum dots.

11 citations

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TL;DR: In this article, the optical properties of an inhomogeneous quantum wire system were studied and the effect of size variation on these optical properties was investigated. But the authors considered the wires are considered to be triangle with infinite potential at the boundaries and the size nonuniformity distribution by a Gaussian function.

Abstract: In this paper, we have studied optical properties of an inhomogeneous quantum wire system. In this regard, we have calculated the absorption coefficients and refractive index changes using density matrix method. We have investigated the effect of size variation on these optical properties. The wires are considered to be triangle with infinite potential at the boundaries. We have described the size nonuniformity distribution by a Gaussian function. It is shown that the optical properties of the quantum wires depend strongly on the wire size distribution described by the parameters a0 and D (the average side length and standard deviation of quantum wire, respectively). It is deduced that the effect of size distribution on the optical properties of triangle quantum wire is noticeable.

9 citations

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TL;DR: In this paper, the optical transitions and absorption spectra of InAs/GaAs quantum dots are computed for short quantum wires with a square base and the variation of the height is Gaussian.

Abstract: InAs/GaAs quantum dots (QDs) grown by various methods do not have the same dimensions in the three axes. This paper reports on expressions for computations of the optical transitions and absorption spectra of InAs/GaAs QDs that have a square base and the variation of the height is Gaussian. The dots were considered to be elongated quantum boxes with square bases having finite potentials at the boundaries. The results are in excellent agreement with reported experimental data of photoluminescence and absorption. The expressions could be successfully applied to short quantum wires.

8 citations

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Hunan University

^{1}TL;DR: In this paper, the authors investigated ballistic phonon transport through Gaussian acoustic nanocavities in a semiconductor nanowire at low temperatures and found that wide band gap and resonant peaks appeared in transmission spectra.

Abstract: We investigate ballistic phonon transport through Gaussian acoustic nanocavities in a semiconductor nanowire at low temperatures. When the transverse widths of acoustic nanocavities takes a Gaussian function, it is found that wide band gap and resonant peaks appear in transmission spectra. The phonon-cavity confined modes exist as the number of the nanocavities is large. The phonon transmission and thermal conductance strongly depend on the number and length of nanocavities. The results suggest that the Gaussian acoustic nanocavities may be useful for controlling thermal conductance artificially and the design of phonon devices to manipulate ballistic phonons in nanophononics.

7 citations

##### References

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Reed College

^{1}TL;DR: A new chapter on symmetries, new problems and examples, improved explanations, more numerical problems to be worked on a computer, new applications to solid state physics, and consolidated treatment of time-dependent potentials as discussed by the authors.

Abstract: Changes and additions to the new edition of this classic textbook include a new chapter on symmetries, new problems and examples, improved explanations, more numerical problems to be worked on a computer, new applications to solid state physics, and consolidated treatment of time-dependent potentials.

3,338 citations

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01 Jan 1999

TL;DR: In this paper, the growth and structural characterisation of self-organized Quantum Dots are discussed. But they do not consider the model of ideal and real quantum Dots.

Abstract: Fabrication Techniques for Quantum Dots. Self-Organization Concepts on Crystal Surfaces. Growth and Structural Characterization of Self-Organized Quantum Dots. Modeling of Ideal and Real Quantum Dots. Electronic and Optical Properties. Electrical Properties. Photonic Devices. References. Index.

2,356 citations

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TL;DR: In this article, the electronic dipole moment and its polarization dependence are analyzed, and it is shown that the gain becomes maximum when the electric field of light is parallel to the longest side of the quantum box.

Abstract: Gain and threshold current density are analyzed for quantum-box lasers where electrons are confined in quantum well three-dimensionally, based on the density-matrix theory of semiconductor lasers with relaxation broadening. The electronic dipole moment and its polarization dependence are first analyzed, and it is shown that the gain becomes maximum when the electric field of light is parallel to the longest side of the quantum box. Calculated gain is about 10 times that of bulk crystal for 100 A × 100 A × 100 A GaAs/Ga 0.8 Al 0.2 As quantum box, and 15 times for Ga 0.47 In 0.53 As/InP quantum box with the same size, respectively. The threshold current density are 45 A/cm2and 62 A/cm2for GRINSCH GaAs/(Ga 0.8 Al 0.2 As-Ga 0.4 Al 0.6 As) and Ga 0.47 In 0.53 As/(Ga 0.28 In 0.72 As 0.6 P 0.4 -InP), respectively, where for the GaInAs/ GaInAsP/InP system the intervalence band absorption and nonradiative recombinations have been assumed to be the same as those obtained for bulk crystals experimentally. These results show the possibility of remarkable reduction in the laser threshold by the quantum-box structures.

1,020 citations

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TL;DR: In this article, a carrier confinement to one and zero degrees of freedom has been achieved in artificial quantum well wires and boxes fabricated in the GaAs•GaAlAs system, which is attributed to transitions arising from ground and excited levels of electrons within these low dimensional structures.

Abstract: Carrier confinement to one and zero degrees of freedom has been achieved in artificial quantum well wires and boxes fabricated in the GaAs‐GaAlAs system. Low‐temperature cathodoluminescence measurements show new luminescence lines attributed to transitions arising from ground and excited levels of electrons within these low dimensional structures.

403 citations

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TL;DR: In this paper, the authors used state-filling photoluminescence experiments to probe the zero-dimensional states and revealed four atomic-like shells (s,p,d,f) with an excitonic inter-sublevel energy spacing which was adjusted to ∼60 meV.

Abstract: Self-assembled strained semiconductor nanostructures have been grown on GaAs substrates to fabricate quantum dot infrared photodetectors. State-filling photoluminescence experiments have been used to probe the zero-dimensional states and revealed four atomic-like shells (s,p,d,f) with an excitonic intersublevel energy spacing which was adjusted to ∼60 meV. The lower electronic shells were populated with carriers by n doping the heterostructure, and transitions from the occupied quantum dot states to the wetting layer or to the continuum states resulted in infrared photodetection. We demonstrate broadband normal-incidence detection with a responsivity of a few hundred mA/W at a detection wavelength of ∼5 μm.

308 citations