Raman scattering near the ( E sub 0 +. Delta. sub 0 ) resonance from (211)-oriented Ga sub 1 minus x In sub x As/GaAs multiple quantum wells
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
- Department of Electrical and Computer Engineering, University of California at Santa Barbara, Santa Barbara, California 93106 (United States)
We present a Raman-scattering study of (211)-oriented Ga{sub 1{minus}{ital x}}In{sub {ital x}}As/GaAs multiple quantum wells grown by use of molecular-beam epitaxy. Off resonance, the Raman scattering satisfied bulk zinc-blende-structure selection rules. Near the ({ital E}{sub 0}+{Delta}{sub 0}) resonance, there is strong LO-phonon Raman scattering in the {ital Z}{prime}({ital X}{prime},{ital X}{prime}){ital {bar Z}} {prime} configuration, where {ital Z}{prime} refers to the growth axis and {ital X}{prime} is in a ({bar 1}11) direction. LO-phonon Raman scattering is forbidden in this configuration by bulk zinc-blende-structure selection rules and does not occur (or at least is much weaker) in (211)-oriented GaAs substrates near this resonance. This Raman process is due to Froehlich-interaction electron-phonon scattering activated by the strain-generated electric fields that occur in the multiple-quantum-well structure. We measure the resonance profile of this Raman process. The scattering efficiency is found to decrease with increasing laser intensity, because of a screening of the strain-generated fields by photoexcited free carriers. We present an electronic-structure calculation that accounts for the energy position of the resonance profile. Based on the electronic-structure results, we discuss simple models for the shape of the resonance profile. A free-carrier screening calculation accurately describes the observed laser-intensity dependence of the efficiency of this Raman process.
- OSTI ID:
- 7201384
- Journal Information:
- Physical Review, B: Condensed Matter; (United States), Vol. 46:3; ISSN 0163-1829
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GALLIUM ARSENIDES
RAMAN SPECTRA
INDIUM ARSENIDES
ELECTRON-PHONON COUPLING
ELECTRONIC STRUCTURE
MOLECULAR BEAM EPITAXY
SELECTION RULES
ARSENIC COMPOUNDS
ARSENIDES
COUPLING
EPITAXY
GALLIUM COMPOUNDS
INDIUM COMPOUNDS
PNICTIDES
SPECTRA
360606* - Other Materials- Physical Properties- (1992-)