In-Plane Electronic Excitations in GaAs/GaAlAs Modulation Doped Quantum Wells
We study the in-plane motion of electrons in modulation doped GaAs/AlGaAs multiple quantum wells by resonant Raman scattering. Electrons from donors incorporated in the barriers of these structures drop into the GaAs wells, forming a multilayered 2D electron gas with very high mobility. The long range interlayer Coulomb interaction couples the in-plane motion of electrons in different wells, even if there is no wave function overlap, as in our present samples. The interlayer Coulomb interaction thus leads to a band of N non-degenerate coupled layer plasmon eigenmodes for an electron system with N sheets. Using resonant Raman scattering we measure the dispersion of these discrete layer plasmon eigenmodes and their coupling with intersubband excitations yielding a very detailed instrument for the characterisation of multilayered electron systems. We measure the single particle excitation spectra as a function of k||. We fit the single particle excitation spectra with the Lindhard formula for the dielectric response function of the 2D electron gas and we show that the electron density and the scattering time can thus be determined optically.
KeywordsSingle Particle Excitation Plasmon Dispersion Dielectric Response Function Resonant Raman Scattering Light Scattering Spectrum
Unable to display preview. Download preview PDF.
- 2.D. Pines and P. Nozières, “The Theory of Fermi Liquids”, W. A. Benjamin Co., Inc., New York, (1966)Google Scholar
- 3.J. Lindhard, Kgl. Danske Videnskap, Mat. Fys. Medd. 28, No. 8. (1954)Google Scholar
- 18.D. C. Hamilton and A. L. McWhorter in Light Scattering Spectra of Solids, p. 309 (ed. G. B. Wright), Springer Verlag, BerlinGoogle Scholar
- 19.A. Mooradian in Light Scattering Spectra of Solids, p. 285 (ed. G. Wright), Springer Verlag, Berlin A. Mooradian and A. L. McWhorter in Light Scattering Spectra of Solids, p. 297 (ed. G. Wright), Springer Verlag, BerlinGoogle Scholar
- 22a.T. Suemoto, G. Fasol and K. Ploog, in Proceedings of the 18th International Conference on the Physics of Semiconductors, Stockholm 1986 (ed. O. Engström), World Scientific Publ. Co. (Singapore), p. 683Google Scholar
- 22b.T. Suemoto, G. Fasol and K. Ploog, Phys. Rev. B 37, (1988) in print.Google Scholar
- 26.D. King-Smith and G. Fasol, to be published.Google Scholar