Eur. Phys. J. B 24, 37-41 (2001)
https://doi.org/10.1007/s100510170019

Effects of tunneling coupling on plasmon modes in asymmetric double-quantum-well structures

¹ Institute of Physics, Chinese Academy of Sciences, PO Box 603, Beijing 100080, PR China
² CCAST (World Laboratory), PO Box 8730, Beijing 100080, PR China and Institute of Physics, Chinese Academy of Sciences, PO Box 603, Beijing 100080, PR China

Corresponding author: ^a c412-1@aphy.iphy.ac.cn

Received: 10 July 2001
Revised: 17 September 2001
Published online: 15 November 2001

Abstract

The collective charge density excitations in asymmetric double-quantum-well (DQW) structures with different tunneling strengths are systematically studied. In particular, the damping properties of the plasmon modes in various tunneling strengths are investigated in detail. It is shown that plasmon modes in asymmetric DQW structures are quite different from those in symmetric DQW systems. In weak tunneling regime, an intra-subband mode with an acoustic-like dispersion relation which is damped in symmetric DQW structures arises and coexists with the optical-like mode while the inter-subband mode is highly damped. With the tunneling strength being increased, the branch gradually becomes undamped and emerges out of the (1 -0) single-particle continuum, whereas the branch gradually approaches the (0 -0) single-particle continuum. In intermediate coupling regime, these three branches of modes coexist undamped. In strong tunneling regime, enters the (0 -0) single-particle continuum and becomes damped. Consequently, only the and modes exist in this regime.