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Title: Photoluminescence from low temperature grown InAs/GaAs quantum dots

Abstract

The authors investigated a set of self-assembled InAs/GaAs quantum dots (QDs) formed by molecular beam epitaxy at low temperature (LT, 250 deg. C) and postgrowth annealing. A QD photoluminescence (PL) peak around 1.01 eV was observed. The PL efficiency quickly quenches between 6 and 40 K due to the tunneling out of the QD into traps within the GaAs barrier. The PL efficiency increases by a factor of 45-280 when exciting below the GaAs band gap, directly into the InAs QD layer. This points towards good optical quality QDs, which are embedded in a LT-GaAs barrier with a high trapping efficiency.

Authors:
; ; ;  [1]
  1. Department of Applied Physics, Eindhoven University of Technology, 5600MB Eindhoven(Netherlands)
Publication Date:
OSTI Identifier:
20960148
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 90; Journal Issue: 11; Other Information: DOI: 10.1063/1.2713803; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ANNEALING; CRYSTAL GROWTH; GALLIUM ARSENIDES; INDIUM ARSENIDES; LAYERS; MOLECULAR BEAM EPITAXY; PHOTOLUMINESCENCE; QUANTUM DOTS; SEMICONDUCTOR MATERIALS; TEMPERATURE DEPENDENCE; TEMPERATURE RANGE 0000-0013 K; TEMPERATURE RANGE 0013-0065 K; TEMPERATURE RANGE 0400-1000 K; TRAPPING; TRAPS; TUNNEL EFFECT

Citation Formats

Sreenivasan, D., Haverkort, J. E. M., Eijkemans, T. J., and Noetzel, R.. Photoluminescence from low temperature grown InAs/GaAs quantum dots. United States: N. p., 2007. Web. doi:10.1063/1.2713803.
Sreenivasan, D., Haverkort, J. E. M., Eijkemans, T. J., & Noetzel, R.. Photoluminescence from low temperature grown InAs/GaAs quantum dots. United States. doi:10.1063/1.2713803.
Sreenivasan, D., Haverkort, J. E. M., Eijkemans, T. J., and Noetzel, R.. Mon . "Photoluminescence from low temperature grown InAs/GaAs quantum dots". United States. doi:10.1063/1.2713803.
@article{osti_20960148,
title = {Photoluminescence from low temperature grown InAs/GaAs quantum dots},
author = {Sreenivasan, D. and Haverkort, J. E. M. and Eijkemans, T. J. and Noetzel, R.},
abstractNote = {The authors investigated a set of self-assembled InAs/GaAs quantum dots (QDs) formed by molecular beam epitaxy at low temperature (LT, 250 deg. C) and postgrowth annealing. A QD photoluminescence (PL) peak around 1.01 eV was observed. The PL efficiency quickly quenches between 6 and 40 K due to the tunneling out of the QD into traps within the GaAs barrier. The PL efficiency increases by a factor of 45-280 when exciting below the GaAs band gap, directly into the InAs QD layer. This points towards good optical quality QDs, which are embedded in a LT-GaAs barrier with a high trapping efficiency.},
doi = {10.1063/1.2713803},
journal = {Applied Physics Letters},
number = 11,
volume = 90,
place = {United States},
year = {Mon Mar 12 00:00:00 EDT 2007},
month = {Mon Mar 12 00:00:00 EDT 2007}
}
  • Photoluminescence (PL) at wavelengths over 1.55 μm from self-assembled InAs quantum dots (QDs) grown on GaAs(001) is observed at room temperature (RT) and 4 K using a bilayer structure with thin cap. The PL peak has been known to redshift with decreasing cap layer thickness, although accompanying intensity decrease and peak broadening. With our strain-controlled bilayer structure, the PL intensity can be comparable to the ordinary QDs while realizing peak emission wavelength of 1.61 μm at 4 K and 1.73 μm at RT. The key issue lies in the control of strain not only in the QDs but also in the cap layer. By combiningmore » with underlying seed QD layer, we realize strain-driven bandgap engineering through control of strain in the QD and cap layers.« less
  • The possibility of controlling the photoluminescence (PL) intensity and its temperature dependence by means of in-growth and postgrowth technological procedures has been demonstrated for InAs/GaAs self-assembled quantum dots (QDs) embedded in an InGaAs quantum well (QW). The improvement of the QD emission at room temperature (RT), achieved due to a treatment with tetrachloromethane used during the growth, is explained by the reduction of the point defect concentration in the capping layer. It is shown that the PL quenching at RT appears again if the samples are irradiated with protons, above a certain dose. These findings are accounted for by themore » variations in the quasi-Fermi level position of the minority carriers, which are related to the concentration of trapping centers in the GaAs matrix and have been calculated using a photocarrier statistical model including both radiative and nonradiative recombination channels. By taking into consideration the temperature dependent distribution of the majority and minority carriers between the QDs, embedding QW and GaAs barriers, our calculated results for the PL intensity reproduce very well the experimentally observed trends.« less
  • The photoluminescence of InAs semiconductor quantum dots overgrown by GaAs in the low-temperature mode (LT-GaAs) using various spacer layers or without them is studied. Spacer layers are thin GaAs or AlAs layers grown at temperatures normal for molecular-beam epitaxy (MBE). Direct overgrowth leads to photoluminescence disappearance. When using a thin GaAs spacer layer, the photoluminescence from InAs quantum dots is partially recovered; however, its intensity appears lower by two orders of magnitude than in the reference sample in which the quantum-dot array is overgrown at normal temperature. The use of wider-gap AlAs as a spacer-layer material leads to the enhancementmore » of photoluminescence from InAs quantum dots, but it is still more than ten times lower than that of reference-sample emission. A model taking into account carrier generation by light, diffusion and tunneling from quantum dots to the LT-GaAs layer is constructed.« less
  • A single layer of self-assembled InAs quantum dots was grown on a GaAs (001) substrate by gas source molecular-beam epitaxy. The quantum dots were overgrown with 65 nm GaAs, 25 nm InGaP, and a 10 nm GaAs etch-stop layer. This was either uncapped or capped with 100 nm of low-temperature (LT)-grown, lattice-matched InGaP (LT-InGaP) or with a SiO{sub 2} layer or Al{sub 2}O{sub 3} layer. Photoluminescence (PL) measurements were made on samples before and after rapid thermal annealing at 550-900 deg.C and for 15-120 s at 650 deg.C. Samples capped with LT-InGaP showed a significant blueshift of the PL peakmore » wavelength for anneals above 575 deg.C. By comparison, for the SiO{sub 2}-capped and uncapped samples, the net blueshift only becomes significant for anneals >700 deg.C, while an Al{sub 2}O{sub 3} cap actually reduces the blueshift and suppresses the intermixing. It appears that the best conditions for spatially controlling the quantum dot intermixing occur with annealing at low temperatures (600-650 deg.C)« less
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