Interface and confined phonons in stepped quantum wells.
P. Kinsler, R. W. Kelsall, P. Harrison.
Institute of Microwaves and Photonics,
School of Electronic and Electrical Engineering,
University of Leeds,
Leeds LS2 9JT,
United Kingdom.
Physica B263, 507 (1999).
The simple symmetric and antisymmetric interface phonon modes of
a square quantum well do not occur in an asymmetric quantum well.
The presence of extra materials and interfaces affects the
potentials of the interface (IF) phonons in addition to the
widely recognised effect on the electronic wavefunctions. Our
"stepped" quantum well structures have phonon modes (potentials)
localised at the well/step interface, so these structures have 8
confined-LO (LC) phonon modes and 10 IF-phonons. We calculate
the non-trivial dispersion of the IF-phonons for increasing
asymmetry (step height); classify the resulting phonon potentials
into "even-like", "odd-like", and "centered"; and explain the
strongest electron--IF-phonon scattering processes in terms of
their matrix elements. The result is that the LC scattering
rates increase with increasing asymmetry, whilst the IF rates
decrease.
Email: Dr.Paul.Kinsler@physics.org