Raman studies of InAs/In0.53Ga0.47As single quantum wells grown on InP substrate by M.B.E.

Abstract

We analyzed using the Raman technique a series of single quantum wells of InAs/In 0.53Ga0.47As at different thicknesses of InAs layer grown on a (100) InP substrate by MBE. These high lattice mismatch systems are particularly interesting for potential applications in the mid-IR wavelength range. The well thickness was between 6 and 12 monolayers. The In 0.53 Ga0.47As grown on an InAs layer is subject to a tensile biaxial strain and the InAs to a compressive one. In the Raman spectra we observed an intense narrow line corresponding to the LO phonon of the InAs layer between a GaAs-like LO mode and a smaller InAs-like LO phonon typical of In0.53Ga0.47As. With the increase of the well thickness the experimental energy shift of the LO phonon of the InAs layer decreases, indicating a smaller strain, whereas the GaAs-like LO phonon of the alloy remains constant and the intensity ratio of these two modes becames smaller. The dominant and sharp features of the InAs LO and GaAs-like LO characterize the good quality of our structures. With the increase of the InAs layer thickness we also observed the appearance and the intensity rise of a weak peak around the frequency of the InAs TO mode. This peak could be associated with the TO mode that is forbidden in our scattering geometry. We believe that this is indicative of a slight deterioration of the structural perfection of the sample with the increase of the well thickness. To our knowledge, this is the first study of vibrational properties of InAs/In 0.53 Ga0.47As single quantum wells grown on InP substrates.