
S. L. Chuang, S. ScmittRink,
D. A. B. Miller, D. S. Chemla "Exciton Green'sfunction approach to
optical absorption in a quantum well with an applied electric field" Physical Review
B, 43, 15001509, (1991). An exciton Green's function is derived and used
to calculate the polarizationdependent optical absorption in a semiconductor quantum well
with an applied electric field. With use of the exciton (or Coulomb) Green'sfunction
approach, the opticalabsorption coefficient due to the bound and continuum states of
excitons can be obtained simultaneously and this approach also takes into account the
coupling between different subband pairs. This is in contrast with the conventional
approach in which the 1s exciton bound state is calculated variationally and the continuum
states are calculated simply using the Sommerfeld enhancement factor from the pure
twodimensional case without the correct quantum size effect. Also, the coupling between
different subband pairs is usually neglected. The authors compare the numerical results of
the Green'sfunction method with those of the commonly used variational method and find
that the variational method overestimates the oscillator strength by 20% for the 1s bound
state and by 50% for the continuum, although the 1s boundstate energy can be quite
accurate. The numerical results using the exciton Green's function are compared with
experimental data and found to be in very good agreement
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