ENERGY-LEVELS OF MAGNETOPOLARONS IN LATERALLY MODULATED 2-DIMENSIONALELECTRONIC SYSTEMS

The Green-function method was adopted to study magnetopolarons in late ral surface superlattices (LSSL's), where lateral periodic potentials due to periodically structured interfaces are introduced into two-dime nsional electronic systems. Numerical calculations were carried out fo r the energy dispersions of magnetopolarons in GaAs LSSL structures wi th periodic potentials along the lateral x direction, such as those pr oduced by deposition of AlAs and GaAs fractional layers on (001) vicin al GaAs substrates. The degenerate magnetopolaron energy levels become dependent on the electron wave vector k(y) in the y direction, formin g magnetopolaron bands. For weak magnetic field (omega(c) much less th an omega(Lo)), the effect of lateral periodic potentials on electron-L O-phonon interaction energies are negligible. The energy dispersions o f magnetopolarons are determined mainly by the energy dispersions of f ree-electron Landau levels in LSSL's. In the resonant region (omega(c) approximate to omega(Lo)), the effect of lateral periodic potentials on electron-LO-phonon interaction energies must be considered in order to obtain the correct magnetopolaron energy dispersions. The energy p inning level for the lowest branch of magnetopolaron energy levels is shifted to lower energy when compared with that in quantum wells with planar interfaces, which changes greatly the energy dispersions of mag netopolaron energy levels in the resonant region. New branches of magn etopolaron energy levels, not present in quantum wells with planar int erfaces, were predicated in LSSL's in the resonant region. The transit ion energies from magnetopolaron ground levels to excited levels form wide bands, which are expected to broaden greatly the cyclotron resona nce absorption spectra of LSSL's.