RAMAN STUDIES OF INAS IN0.53GA0.47AS SINGLE QUANTUM-WELLS GROWN ON INP SUBSTRATE BY MBE/

We analyzed using the Raman technique a series of single quantum wells of InAs/In0.53Ga0.47As at different thicknesses of InAs layer grown o n a (100) InP substrate by MBE. These high lattice mismatch systems ar e particularly interesting for potential applications in the mid-IR wa velength range. The well thickness was between 6 and 12 monolayers. Th e In0.53Ga0.47As grown on an InAs layer is subject to a tensile biaxia l strain and the InAs to a compressive one. In the Raman spectra we ob served an intense narrow line corresponding to the LO phonon of the In As 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 decrease s, indicating a smaller strain, whereas the GaAs-like LO phonon of the alloy remains constant and the intensity ratio of these two modes bec ames smaller. The dominant and sharp features of the InAs LO and GaAs- like LO characterize the good quality of our structures. With the incr ease of the InAs layer thickness we also observed the appearance and t he intensity rise of a weak peak around the frequency of the InAs TO m ode. This peak could be associated with the TO mode that is forbidden in our scattering geometry. We believe that this is indicative of a sl ight deterioration of the structural perfection of the sample with the increase of the well thickness. To our knowledge, this is the first s tudy of vibrational properties of InAs/In0.53Ga0.47As single quantum w ells grown on InP substrates.