EXCITON RESONANCE REFLECTIVITY STUDY OF QUANTUM-WELL WIRES

We report on the first observation of the exciton resonant reflection from a directly grown array of isolated quantum-well-wires. Structures contaned 30 GaAs/AlAs double layers were grown on (311) GaAs substrat e by conventional elemental source MBE. GaAs wire-like clasters with a n orientation along [233BAR] and size of 32/10.2 angstrom were introdu ced inside one of the central AlAs layers. The expected distance betwe en nearest clusters is about 160 angstrom. In spite of much smaller ef fective volume occupied by excitons in these clusters, as compared to that in a single quantum well, the quantum-well-wire structures demons trate much lager resonance amplitude of the reflection spectra. We ext racted excitonic parameters from these spectra and found that the exci ton oscillator strength in the quantum-well-wires is more than 10 time higer than that in the enviroment superlattice. A 30% anisotropy of t he exciton oscillator strength in the quantum-well-wire have been obse rved. The theory of non-local dielectric responce is extended to calcu late reflection spectra from the structures with a grating of quantum- well-wires. A functional relationship between the reflection coefficie nt and the envelope wave function of an exciton in the structure has b een established.