S. De-leon et B. Laikhtman, Exciton wave function, binding energy, and lifetime in InAs/GaSb coupled quantum wells, PHYS REV B, 61(4), 2000, pp. 2874-2887
We studied theoretically excitons in narrow-coupled InAs/GaSb quantum wells
where there is not any overlap between the InAs conduction subband and the
GaSb valence subband. In this case, excitons do not exist in the equilibri
um and the luminescence of pumped excitons can be observed. We calculated t
he exciton binding energy making use of the variational method. The resulti
ng binding energy is around 4 meV. We also calculated the exciton lifetime
for both radiative recombination and nonradiative recombination. Due to the
unique band alignment of InAs/GaSb, the recombination can happen via two c
hannels: first, mixing of the conduction band of InAs with the valence band
of GaSb and second, electron tunneling from InAs conduction band to GaSb c
onduction band and hole tunneling from GaSb valence band to InAs valence ba
nd. The fastest recombination process is the radiative process in the secon
d channel. The lifetime varies with the well widths from 45 ps for narrow w
ells to 400 ps for wider wells.