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
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.
PACS: 73.21.-b – Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2001