Infrared spectroscopy of self-organized InAs nanostructures grown on InAlAs/InP(001) for infrared photodetection applications

InAs nanostructures on InAlAs/InP(0 0 1) have been fabricated using Stransk i-Krastanov growth mode. Depending on growth conditions, a full coverage of the InAlAs surface by either InAs quantum wires or quantum dots can be ach ieved. Giant intraband absorptions are observed at mid-infrared wavelengths . The intraband resonances are strongly polarized in the layer plane as a c onsequence of the quantum confinement along the [1 1 0] direction. The abso rption at normal incidence reaches 26% for 10 layers of n-doped (1 x 10(12) cm(-2)) InAs elongated dots. We also report on femtosecond pump-probe expe riments aimed at measuring the electron capture time. Typical times range f rom 3 ps for broad wires to 6 ps for narrow wires. (C) 2001 Elsevier Scienc e B.V. All rights reserved.