Record wavelength emitted from InAs/GaAs quantum dots


Record wavelength emitted from InAs/GaAs quantum dots (maximum at 1580 nm).

Data transfer in optical waveguides uses about 1300 and 1550 nm (windows of silicon waveguides – minimal dispersion and attenuation). A simple InAs quantum dot (QD) structure prepared in Stranski-Krastanow growth mode by metalorganic vapour phase epitaxy technique (MOVPE) is usually emitting around 1200 nm. In order to shift emission wavelength into desired range, InAs QDs have to be prepared in more sophisticated structures (vertical stacking of QDs, strain reduction with the use of covering or pseudomorphic matrix layers).


We managed to reach the record maximum photoluminescence wavelength from InAs QDs prepared on GaAs substrate: 1577 nm (at room temperature). The composition, thickness as well as growth rate of InGaAs layer covering InAs QD, which reduces strain in QDs and also stabilizes their size and shape, were important for obtaining this wavelength [1].

A transmission electron microscope picture of the structure with quantum dots. The dot is covered by 5 nm thick InGaAs strain-reducing layer (SRL - red) and 30 nm thick GaAs capping layer (Cap - green). It is all prepared on GaAs substrate (blue). The strain in this structure can be seen as a black region in the vicinity of quantum dot.


[1] P. Hazdra, J. Oswald, V. Komarnitskyy, K. Kuldová, A. Hospodková, J. Vyskočil, E. Hulicius, J. Pangrác, InAs/GaAs quantum dot structures emitting in the 1.55 μm band, Mat. Sci. Eng. A - Struct. 6 (2009) 012007-1 - 012007-4.