Response of excitonic absorption spectra to photoexcited carriers in GaAs quantum wells

Journal Article · Sun Nov 15 04:00:00 EST 1992 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.46.13452· OSTI ID:7038228

Wake, D R; Yoon, H W; Wolfe, J P ^[1]; Morkoc, H ^[2]

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1. Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)
2. Coordinated Science Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)

The changes induced in the optical-absorption spectrum of a GaAs/Al{sub {ital x}}Ga{sub 1{minus}{ital x}}As multiple-quantum well due to photoexcited carrier distributions are reexamined. We use a picosecond pump-probe technique to excite carriers in a sample having wells of thickness 210 A and barriers of thickness 100 A. We find that for densities up to 1{times}10{sup 11} cm{sup {minus}2} the peak of the exciton line of the lowest-energy exciton becomes bleached; however the spectrally integrated area does not change, indicating that the carriers reduce the absorption peak by collision broadening rather than by phase-space filling or exchange. We also observe shifts of the exciton line to higher energy ( blueshift'') or to lower energy ( redshift'') depending on the energy of the pump photons. The shift can be ascribed to competing effects of band-gap renormalization and the change in the binding energy of the exciton, although a detailed theoretical description is still needed.

• DOE Contract Number: AC02-76ER01198
• OSTI ID: 7038228
• Journal Information: Physical Review, B: Condensed Matter; (United States), Journal Name: Physical Review, B: Condensed Matter; (United States) Vol. 46:20; ISSN PRBMD; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360606* -- Other Materials-- Physical Properties-- (1992-)
ABSORPTION SPECTRA
ALUMINIUM ARSENIDES
ALUMINIUM COMPOUNDS
ARSENIC COMPOUNDS
ARSENIDES
BINDING ENERGY
CHARGE CARRIERS
ENERGY
EXCITONS
GALLIUM ARSENIDES
GALLIUM COMPOUNDS
IRRADIATION
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
PNICTIDES
PULSED IRRADIATION
QUASI PARTICLES
SPECTRA