Intraband spectroscopy of self-organized InAs/InAlAs nanostructures grown on InP(0 0 1)

InAs nanostructures on InAlAs/InP(0 0 1) have been fabricated using Stranski-Krastanov growth mode. Depending on growth conditions, a full coverage of the InAlAs surface by either InAs strings of elongated dots or isolated dots can be achieved. Giant intraband absorptions are observed at mid-infrared wavelengths in both nanostructures. The intraband resonances are strongly polarized in the layer plane as a consequence of the quantum confinement along either [1 1 0] and [1 - 10] directions.