TY - JOUR
T1 - Coherent dynamics of excitons in an island-inserted GaAs/AlAs quantum well structure
T2 - Suppression of phase relaxation and a deep quantum beat
AU - Matsusue, Toshio
AU - Akiyama, Hidefumi
AU - Saiki, Toshibaru
AU - Ramkumar, Chari
AU - Shirane, Masayuki
AU - Shimano, Ryo
AU - Kuwata-Gonokami, Makoto
AU - Sakaki, Hiroyuki
PY - 1999
Y1 - 1999
N2 - The degenerate four-wave mixing technique in the self-diffraction geometry is employed to investigate a novel GaAs/AlAs quantum well microstructure. Time-integrated transient measurements are carried out to study the coherent dynamics of excitons in a GaAs quantum well with AIAs islands inserted at the center of the well (IIQW) in excitation densities from 6 × 109 to 1.5 × 109 cm-2. The decay of the time-integrated self-diffracted signal shows slower dephasing for the IIQW compared to that of a normal quantum well (NQW) without island insertion. The dephasing rate is found to increase slightly in the IIQW, while it is found to increase sharply in the NQW with the excitation density. A deep beat with a period of 1.45 ps, which disappears for co-circular polarization configuration, is observed in the decay of the self-diffracted signal in the IIQW. The detcction-energy-resolved measurement reveals that the modulation of the beat increases up to full depth at low detection energy with respect to the peak energy of the self-diffracted signal. The dependence on detection energy and on polarization configuration shows that the beat is a quantum beat due to biexcitonic effect, which is enhanced by localization due to island insertion.
AB - The degenerate four-wave mixing technique in the self-diffraction geometry is employed to investigate a novel GaAs/AlAs quantum well microstructure. Time-integrated transient measurements are carried out to study the coherent dynamics of excitons in a GaAs quantum well with AIAs islands inserted at the center of the well (IIQW) in excitation densities from 6 × 109 to 1.5 × 109 cm-2. The decay of the time-integrated self-diffracted signal shows slower dephasing for the IIQW compared to that of a normal quantum well (NQW) without island insertion. The dephasing rate is found to increase slightly in the IIQW, while it is found to increase sharply in the NQW with the excitation density. A deep beat with a period of 1.45 ps, which disappears for co-circular polarization configuration, is observed in the decay of the self-diffracted signal in the IIQW. The detcction-energy-resolved measurement reveals that the modulation of the beat increases up to full depth at low detection energy with respect to the peak energy of the self-diffracted signal. The dependence on detection energy and on polarization configuration shows that the beat is a quantum beat due to biexcitonic effect, which is enhanced by localization due to island insertion.
KW - Biexciton
KW - Degenerated four-wave mixing
KW - Exciton
KW - GaAs/AlAs heterostructure
KW - Island-inserted quantum well
KW - Localization
KW - Phase relaxation
KW - Quantum beat
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U2 - 10.1143/jjap.38.2735
DO - 10.1143/jjap.38.2735
M3 - Article
AN - SCOPUS:0032654333
VL - 38
SP - 2735
EP - 2740
JO - Japanese Journal of Applied Physics, Part 1: Regular Papers & Short Notes
JF - Japanese Journal of Applied Physics, Part 1: Regular Papers & Short Notes
SN - 0021-4922
IS - 5 A
ER -