Wave vector dispersion of excitations of the two-dimensional electron gas from light scattering using a grating coupler

Abstract We determined the wave vector dispersion of elementary excitations of the two-dimensional electron gas (2DEG) like plasmons and intersubband excitations of the charge (CDE) and spin density (SDE) by inelastic light scattering using a grating coupler. The 2DEG forms in a modulation-doped AlGaAs/GaAs single quantum well sample on top of which we evaporated a metallic grating. In this way, in backscattering geometry with incident light perpendicular to the plane of the 2DEG, light can couple to elementary excitations with finite wave vectors in the range from 10 4 to 10 6 cm −1 .