Phonon-Plasmon Interaction in Tunnelling GaAs/AlAs Superlattices Grown on (311) and (100) Substrates

摘要

Phonon-plasmon coupling in Si doped GaAs_n/AlAs_m superlattices (SLs), grown on (001), (311)A and (311) B substrates, was studied using Raman spectroscopy. The shift and broadening of Raman peaks in doped SLs comparing with not doped ones were observed. When GaAs layers were thinned from 1.7 to 0.17 nm, the coupled phonon-plasmon modes became 3D-like, and the interaction of plasmons with LO-phonons of AlAs type take place. The phonon-plasmon interaction in the case of SLs was numerically modelling on the base of microscopic approach. The qualitative agreement of the experiment and the calculations took place. The difference in dispersion of the coupled phonon-plasmon modes for SLs grown on facet surface (311)A and surface (311)B was observed. This is probably due to differences in electron spectra of such SLs caused by difference in shapes of GaAs quantum objects self organising under condition of the surface reconstructions.