Tuning the intersubband absorption in strained AlAsSb/InGaAs quantum wells towards the telecommunications wavelength range

We study the intersubband absorption in Si doped AlAsSb/InGaAs quantum wells (QWs) grown on InP substrates by molecular beam epitaxy. The investigated multiple QW structures contain strained In0.78Ga0.22As layers and additional AlAs layers for strain compensation. By varying the nominal QW width from 3 to 9 ML (monolayer) a minimum central absorption wavelength of 1.76 mu m is found for a 5 ML thick QW. Simulations of these experimental results using a self-consistent Schrodinger-Poisson solver show a deviation from the perfect squarelike potential caused by intermixing effects at the interfaces. These blurred interfaces are also revealed by transmission electron microscopy measurements. (c) 2006 American Institute of Physics.