ISSN:
1432-0630
Keywords:
78.65.-s
;
73.20.Dx
;
78.55.-m
;
73.60.Br
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
Abstract Excitonic resonance structures in GaAs/AlAs multiple quantum well heterostructures with varying barrier-layer thicknessesL B down to 1.3 nm are investigated for two sets of samples with the nominal well widths ofL Z =9.2 and 6.4 nm, by 2K photoluminescence excitation spectroscopy. The observed resonance energies of then=1 heavyhole (1 hh) and light-hole (1 lh) free excitons imply that quantum confinement effects persist at least down to the decreased barrier-layer thickness ofL B =1.3 nm. This result is inconsistent with the red shifts expected from the simple well-coupling theory within the one-band Kronig-Penney model at theГ point. Instead, blue shifts of 6–8 meV (8–17 meV) are observed for the 1 hh (1 lh) excitonic resonance peaks whenL B is decreased from 10 to 2 nm. A relative decrease of the oscillator strength of the 1 lh transition compared to the 1 hh transition is also observed asL B is decreased. These results manifest important effects of the indirect-gap barrier material for the actual wavefunction matching across the interface and the breakdown of the envelope function approach to GaAs/AlAs quantum well heterostructures with ultrathin barriers.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00624599
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