Experimental and theoretical study of polarization-dependent optical transitions in InAs quantum dots at telecommunication-wavelengths (1300-1500 nm)

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2011
Authors
Usman, Muhammad
Heck, Susannah C.
Clarke, Edmund
Spencer, Peter
Ryu, Hoon
Murray, Ray
Klimeck, Gerhard
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AIP Publishing
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Abstract
The design of some optical devices, such as semiconductor optical amplifiers for telecommunication applications, requires polarization-insensitive optical emission at long wavelengths (1300-1550 nm). Self-assembled InAs/GaAs quantum dots (QDs) typically exhibit ground state optical emissions at wavelengths shorter than 1300 nm with highly polarization-sensitive characteristics, although this can be modified by the use of low growth rates, the incorporation of strain-reducing capping layers, or the growth of closely-stacked QD layers. Exploiting the strain interactions between closely stacked QD layers also affords greater freedom in the choice of growth conditions for the upper layers, so that both a significant extension in their emission wavelength and an improved polarization response can be achieved due to modification of the QD size, strain, and composition. In this paper, we investigate the polarization behavior of single and stacked QD layers using room temperature sub-lasing-threshold electroluminescence and photovoltage measurements, as well as atomistic modeling with the NEMO 3-D simulator. A reduction is observed in the ratio of the transverse electric ('TE) to transverse magnetic (TM) optical mode response for a GaAs-capped QD stack as compared to a single QD layer, but when the second layer of the two-layer stack is InGaAs-capped, an increase in the TE/TM ratio is observed, in contrast to recent reports for single QD layers. (C) 2011 American Institute of Physics. [doi:10.1063/1.3587167]
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Quantum dots , Polarization , III-V semiconductors , Ground states , Wave functions
Citation
Usman, M., Heck, S., Clarke, E., Spencer, P., Ryu, H., Murray, R. and Klimeck, G. (2011) 'Experimental and theoretical study of polarization-dependent optical transitions in InAs quantum dots at telecommunication-wavelengths (1300-1500 nm)', Journal of Applied Physics, 109(10), 104510 (8pp). doi: 10.1063/1.3587167
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© 2011, American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. The following article appeared in Usman, M., Heck, S., Clarke, E., Spencer, P., Ryu, H., Murray, R. and Klimeck, G. (2011) 'Experimental and theoretical study of polarization-dependent optical transitions in InAs quantum dots at telecommunication-wavelengths (1300-1500 nm)', Journal of Applied Physics, 109(10), 104510 (8pp). doi: 10.1063/1.3587167 and may be found at http://aip.scitation.org/doi/10.1063/1.3587167