Lc. Andreani et al., EFFECT OF INHOMOGENEOUS BROADENING ON OPTICAL-PROPERTIES OF EXCITONS IN QUANTUM-WELLS, Physical review. B, Condensed matter, 57(8), 1998, pp. 4670-4680
The effect of inhomogeneous broadening oh exciton-light coupling in qu
antum wells (QW's) is studied by a semiclassical model, in which the e
xciton resonance frequency is assumed to have a Gaussian distribution.
The presence of disorder may be observed in absorption, but not in re
flectivity spectra. The integrated absorption of light in single and m
ultiple QW's is nonzero only in the presence of a finite damping and i
ncreases with enhancement of either homogeneous or inhomogeneous broad
ening: only when broadening is larger than the exciton radiative width
does the integrated absorption attain the saturation value expected f
rom the exciton oscillator strength and the number of QW's. This behav
ior is similar to that of exciton-polariton absorption in bulk semicon
ductors, but unlike the bulk case it is not due to spatial dispersion.
For multiple QW's, QW's in a microcavity and in a thick film of bulls
, in general, disorder produces a decrease of the period of oscillatio
ns in the time-resolved transmission and yields a faster decay of the
signal. However, inhomogeneous broadening is also found to lead to bea
tings in the time-resolved transmission or reflection of light from a
single QW: the oscillations, which originate from interference between
upper and lower wings of the exciton distribution, maybe observed in
high-quality samples. [S0163-1829(98)06507-2].