Quantum dots based on InAs/GaAs are perspective structures for active zones of lasers and optical amplifiers used for data transmission via optical fibre waveguides.
We prepare InAs/GaAs quantum dots using Stranski-Krastanow growth mode in MOVPE (Metal-Organic Vapour Phase Epitaxy) laboratory of Semiconductor department.
We found that it is possible to obtain information about growth rate of InAs strained layer (maximum at 1 monolayer of InAs) by means of the detection of reflectance anisotropy of epitaxial surface at 4.2 eV. Furthermore, it is possible to observe in real-time when quantum dots start to be formed and when their development is terminated [1]. In this manner, we are able to optimise technological parameters more easily during quantum dot growth, i.e. to prepare structures with better parameters – suitable wavelength and high intensity of photoluminescence – and simultaneously reduce costs of preparation of these structures.
An AFM image of quantum dots.
[1] A. Hospodková, J. Vyskočil, J. Pangrác, J. Oswald, E. Hulicius, K. Kuldová, Surface processes during growth of InAs/GaAs quantum dot structures monitored by reflectance anisotropy spectroscopy, Surf. Sci. 604 (2010) 318 - 321.