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

Journal Article · Sun Nov 15 00:00:00 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), Vol. 46:20; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

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