Infrared photoreflectance spectroscopy of AlGaAsSb-, InGaSb-based quantum wells

Infrared photoreflectance (IRPR) has been used for the first time to characterisation of InGaSb-, AlGaAsSb-based quantum well (QW) structures. This contactless and nondestructive method is very sensitive to optical transitions and enables detection of confined states (ground and excited states) in a quantum well structure. The measurements have been carried at low temperature to increase the efficiency of photomodulation. Sharp and well-resolved PR resonances, related to optical transitions originating from both the GaSb buffer and the quantum wells have been observed. The experimental energies agree with those calculated by means of the envelope-function model adopting the accepted values of materials parameters and including strains. The results show that photoreflectance technique is powerful, easy to use and inexpensive tool, which give a lot of information about the investigated low-dimensional semiconductor structures designed for near infrared applications.