||A. M. Fox, D. A. B. Miller, G. Livescu, J.
E. Cunningham, W. Y. Jan, "Quantum well carrier sweep out: relation to
electroabsorption and exciton saturation" IEEE J. of Quantum Electronics, 27,
The authors studied the effects of changing the barrier design
of GaAs-Al/sub x/Ga/sub 1-x/As quantum wells on the electroabsorption, exciton saturation,
and carrier sweep-out times. Five samples with x values ranging from 0.2 to 0.4 and
barrier thicknesses from 35 to 95 AA were studied. Within this range, the authors find
that the electroabsorption is not very sensitive to the barrier thickness, but that the
ionization field of the excitons approximately doubles for an increase of x from 0.2 to
0.4. The samples with high, thick barriers have lower internal quantum efficiencies than
those with low, thin barriers. It was found that the exciton saturation intensity
increases with increasing applied field, and decreasing barrier thickness or height.
Time-resolved electroabsorption measurements confirm the variation in sweep-out rates
between samples, and indicate that the escape mechanism at low field is probably a
thermally-assisted tunneling process
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