Theoretical estimation of optical absorption coefficient inside an InAs/InGaAs semiconductor Quantum Dot (original) (raw)
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International Journal of Optics and Applications, 2014
In recent years, effects that are concerned with quantum nature of light have attracted too attention. The more the devices become smaller, the quantum effects become more apparent. Single photon sources are the essential devices in many quantum information processes, such as quantum key distribution. One way for realization of single photon sources is to exploit quantum dots. Single quantum dot has the ability of single photon emission, which can be analyzed by quantum electrodynamics. Emission from quantum dots under special circumstances has non-classically effects. In present paper, first we extract a novel relation for computing optical absorption coefficient in k.p framework and three dimensional carrier confinements. Then with this relation, we analyze an electrically driven single photon source that its wavelength is more tunable in the fabrication process. This tunability is a consequence of exploiting a quantum dot surrounded by a quantum well. Eight-band k.p modeling is used for extracting of energy levels and spectral analyzing of quantum dot. In this work, we investigated theoretically, the emission from an InAs/InxGa1-xAs quantum dot. Using InxGa1-xAs alloy around the InAs provides us a freedom for tuning the source in a wide range of wavelengths. Eventually it is shown that for x=0.53, the peak gain occurs in 1.3µm wavelength which is used widely in fast fiber optic communication.
Intraband light absorption in InAs/GaAs quantum dots covered with InGaAs quantum wells
Semiconductor Science and Technology, 2006
The spectral and polarization dependences of intraband light absorption in n-and p-doped structures with InAs/GaAs quantum dots covered by InGaAs layers were studied experimentally and theoretically. The transmittance of p-and s-polarized mid-infrared radiation was studied in a multi-pass sample geometry. Elastic strain, piezoelectric fields and a complex valence band structure were taken into account in calculations of the energy spectrum, the carrier wavefunctions and intraband optical matrix elements. The experimentally determined value of the absorption cross section corresponding to |0 0 0 →|0 0 1 intraband electron transitions is 4.1 × 10 −15 cm 2. Light absorption related to intraband hole transitions was found to be significantly smaller. The dispersion of the dot sizes was evaluated using the experimentally determined spectral widths of intraband absorption peaks.
Absorption spectroscopy of single InAs self-assembled quantum dots
Physica E: Low-dimensional Systems and Nanostructures, 2004
Excitonic transitions of single InAs self-assembled quantum dots were directly measured at 4:2 K in an optical transmission experiment. We use the Stark e ect in order to tune the exciton energy of a single quantum dot into resonance with a narrow-band laser. With this method, sharp resonances in the transmission spectra are observed. The oscillator strengths as well as the homogeneous line widths of the single-dot optical transitions are obtained. A clear saturation in the absorption is observed at modest laser powers. ?
Light absorption and emission in InAs/GaAs quantum dots and stepped quantum wells
2002
The results of optical phenomena investigations in quantum dot and quantum well structures under interband optical pumping are presented. Interband and intraband light absorption in nanostructures with quantum dots has been studied experimentally and theoretically. Photoluminescence and interband light absorption in stepped quantum wells have been investigated including PL studies under picosecond optical pumping. Experimental results have been compared with results of calculation of energy spectrum and transition probabilities. It is shown that inversion of population exists between the third and second excited levels of stepped quantum well.
Non-classical Photon Emission from a Single InAs/InP Quantum Dot in the 1.3-µm Optical-Fiber Band
Japanese Journal of Applied Physics, 2004
We report the first observation of single-photon emission from a single InAs/InP quantum dot at a telecommunication wavelength. The single quantum dot was developed through a `double-cap' growth method using metalorganic chemical vapor deposition, and its emission covers a wide spectral range of the optical telecommunication band. Using a pulsed excitation source and gated single-photon detection modules, we observed a photon antibunching behavior through a single-mode optical fiber for an isolated exciton emission line at 1277.1 nm in the O-band (1.3 µm).
Optical characteristics of single InAs∕InGaAsP∕InP(100) quantum dots emitting at 1.55 μm
Applied Physics Letters, 2006
We have studied the emission properties of individual InAs quantum dots (QDs) grown in an InGaAsP matrix on InP(100) by metal-organic vapor-phase epitaxy. Low-temperature microphotoluminescence spectroscopy shows emission from single QDs around 1550 nm with characteristic exciton-biexciton behavior, and a biexciton antibinding energy of more than 2 meV. Temperaturedependent measurements reveal negligible optical-phonon induced broadening of the exciton line up to 50 K, and emission from the exciton state clearly persists above 70 K. Furthermore, we find no measurable polarized fine structure splitting of the exciton state within the experimental precision. These results are encouraging for the development of a controllable photon source for fiber-based quantum information and cryptography systems.
Absorption coefficient for the intraband transitions in quantum dot materials
Progress in Photovoltaics: Research and Applications, 2012
In this paper, we present calculations of the absorption coefficient for transitions between the bound states of quantum dots grown within a semiconductor and the extended states of the conduction band. For completeness, transitions among bound states are also presented. In the separation of variables, single band kÁp model is used in which most elements may be expressed analytically. The analytical formulae are collected in the appendix of this paper. It is concluded that the transitions are strong enough to provide a quick path to the conduction band for electrons pumped from the valence to the intermediate band.
Carrier-Carrier Correlations and Their Effect on Optically Excited Single Semiconductor Quantum Dots
physica status solidi (b), 2000
We resolve spatially, spectroscopically and temporally the photoluminescence emission from single self-assembled In(Ga)As/GaAs quantum dots. The rich photoluminescence spectrum and its evolution with time after pulse excitation and with the density of excitation is experimentally measured and analyzed using a theoretical multiexciton model. From the quantitative agreement between the measured and calculated spectra, the radiative lifetime of a single quantum dot exciton is unambiguously determined. E. Dekel et al.: Carrier±Carrier Correlations and Their Effect on Excited QDs
Photoluminescence of InAs/GaAs quantum dots under direct two-photon excitation
Scientific Reports, 2020
Self-assembled quantum dots grown by molecular beam epitaxy have been a hotbed for various fundamental research and device applications over the past decades. Among them, InAs/GaAs quantum dots have shown great potential for applications in quantum information, quantum computing, infrared photodetection, etc. Though intensively studied, some of the optical nonlinear properties of InAs/GaAs quantum dots, specifically the associated two-photon absorption of the wetting and barrier layers, have not been investigated yet. Here we report a study of the photoluminescence of these dots by using direct two-photon excitation. The quadratic power law dependence of the photoluminescence intensity, together with the ground-state resonant peak of quantum dots appearing in the photoluminescence excitation spectrum, unambiguously confirms the occurrence of the direct two-photon absorption in the dots. A three-level rate equation model is proposed to describe the photogenerated carrier dynamics in ...