COLLECTIVE EXCITATION IN GAAS-ALXGA1-XAS QUANTUM WIRES - MULTISUBBANDMODEL

The effects of the potential barrier height on the collective excitati ons of an electron gas confined in a GaAs-AlxGa1-xAs quantum wire of r ectangular cross section are investigated theoretically by using the s elf-consistent field approximation theory proposed by Singwi, Tosi, La nd, and Sjolander (STLS) [Phys. Rev. 176, 589 (1968)]. For several pot ential barrier heights, we calculated the effective potential, plasmon energy, structure factor, and pair-correlation function, considering a three-subband model with only the lowest subband populated by electr ons. We verified that the intersubband plasmon is more sensitive to th e potential barrier height variation than the intrasubband plasmon. We also observed that the confining potential effect decreases with the increasing of the wire width. The random-phase approximation results a re also presented by comparison with the STLS results and significant differences were found.