Biomedical Engineering Reference
In-Depth Information
+ ε =
-1
Field
(V/cm
-1
)
10,000
4.8 × 10
4
1.6 × 10
4
5,000
0
0
1.48
1.43
(a)
Photon energy (eV)
+ ε =
7.3 × 10
4
10,000
4.7 × 10
4
5,000
1.0 × 10
4
Field
(V/cm
-1
)
0
1.48
1.43
(b)
Photon energy (eV)
FIGURE 3.19
Absorption spectra at various electric fields for applied (a) parallel, (b) perpendicular, to the
QW layer. The distortion is shown schematically. The zeros, indicated by dashed lines, are
displaced for clarity. (After Chemla, D.S. et al.,
J. Opt. Soc. Am
., 2(7), 1162, 1985.)
known as the QCSC and is analogous to the Franz-Keldysh effect or band-
edge shift observed in bulk semiconductors. The shift in exciton energy lev-
els is described as a function of perpendicular electric field intensity. The
method used to describe the energy level of excitons in MQWS is to calculate
the energy of one exciton in a single QW [41].
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