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Exciton/free-carrier radiative emission ratio and temperature dependence of exciton lifetime for CdZnSSe/ZnSSe single quantum wells
Author(s): H. Wang; Kam Sing Wong; George K.L. Wong
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Paper Abstract

The time-integrated and time-resolved photoluminescence (PL) of Cd0.3Zn0.7S0.06Se0.94/ZnS0.06Se0.94 single quantum wells (QW) have been studied at various temperatures. The time-resolved PL is obtained by sum frequency conversion technique with 300 fs resolution. The PL line shape analysis based on a simple statistical model including both excitons and free-carriers showed that free exciton radiative recombination dominates the PL emission even at room temperature. However, free-carrier recombination contributed significantly to the emission spectrum down to 77 K. The free excitons are stable up to room temperature because of the large exciton binding energy and strong confinement of electrons and holes in these QWs. The free exciton decay time is approximately 300 ps at 130 K and it increases linearly to 1 ns at 295 K. This is the first time that exciton radiative recombination and linear temperature dependence of exciton lifetime is observed up to room temperatures for wide-gap II-VI QWs. This is due to the excellent quality of the samples and the strong confinement of electrons and holes in the QWs studied. This linear increase in exciton lifetime with temperature agrees with the theoretical prediction by considering the conservation of momentum requirement for radiative recombination for excitons in QW.

Paper Details

Date Published: 24 May 1999
PDF: 12 pages
Proc. SPIE 3624, Ultrafast Phenomena in Semiconductors III, (24 May 1999); doi: 10.1117/12.349287
Show Author Affiliations
H. Wang, Hong Kong Univ. of Science and Technology (Hong Kong)
Kam Sing Wong, Hong Kong Univ. of Science and Technology (Hong Kong)
George K.L. Wong, Hong Kong Univ. of Science and Technology (Hong Kong)

Published in SPIE Proceedings Vol. 3624:
Ultrafast Phenomena in Semiconductors III
Kong-Thon F. Tsen, Editor(s)

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