Comparison of the collective excitation spectra of three-, two- and one-dimensional electron systems

Collective excitation spectra of three-, two-, and one-dimensional electron systems are deduced theoretically in detail on the basis of random phase a pproximation in the one subband occupancy limit. The theoretical results sh ow that the plasma energy of the three-dimensional electron gas (3DEG), ome ga (q), starts from a large value even at q = 0, while the plasma energy of the two-dimensional electron gas (2DEG) and one-dimensional (1D) quantum w ires start from zero. In contrast to the corresponding plasmon of 3DEG and 2DEG, the dispersion relation of 1D plasmon exhibits a logarithmic dispersi on at small wave vectors and the characteristic size of the wire appears in the formula. The numerical results show that the wave vector- and energy r egions where the 1D plasmons can long exist are much wider than those of 3D and 2D plasmons. This suggests that the collective excitations may play a more important role on the electron transport properties in 1D quantum wire s than in 2D and 3D electron systems, (C) 2001 Elsevier Science B.V. All ri ghts reserved.