E(1)-GAP RESONANT ENHANCEMENT OF THE RAMAN-SCATTERING FROM HIGHLY STRAINED INAS INP SHORT-PERIOD SUPERLATTICES

We report a Raman study of confined InAs-like and InP-like longitudina l optical and interface phonons in highly strained short-period superl attices grown coherently on (001) InP substrates by Atomic Layer Epita xy. A resonant enhancement of the InAs Raman scattering cross-section at the E(1) gap of InAs appears as the InAs layer thickness increases beyond 2 monolayers. This enhancement indicates that the scattering in volves E(1)-gap excitons strongly confined in the InAs wells when this gap is created. InAs-like confined longitudinal-optic phonons of A(1) and B-2 symmetries are observed in both z(x,x)(z) over bar polarized and z(x,y)(z) over bar depolarized configurations under InAs E(1)-gap resonant excitation. This relaxation of the selection rules is analyze d in terms of resonant impurity-iuduced scattering. It indicates that the symmetry of the exciton wave functions at the L point, which is di fferent from those at the Gamma point, allows intraband coupling of he avy-hole and light-hole states via the deformation- potential interact ion.