ISSN:
1432-0630
Schlagwort(e):
78.65.-s
;
71.70.-d
;
68.55.+b
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Maschinenbau
,
Physik
Notizen:
Abstract Low-temperature photoluminescence measurements on nominally undoped AlxGa1−xAs/GaAs quantum well heterostructures (QWHs) grown by molecular beam epitaxy (MBE) exemplified the exclusivelyintrinsic free-exciton nature of the luminescence under moderate excitation conditions. Neither any spectroscopic evidence for alloy clustering in the AlxGa1−xAs barriers nor any extrinsic luminescence due to recombination with residual acceptors has been detected in single and double QWHs when grown at 670 °C under optimized MBE growth conditions. Carrier confinement in AlxGa1−xAs/GaAs QWHs starts at a well width ofL z≌30 nm when x≌0.25. The minor average well thickness fluctuation ofΔL z=4×10−2nm as determined from the excitonic halfwidth allowed the realization of well widths as low asL z=1 nm and thus a shift of the free-exciton line as high as 2.01 eV which is close to the conduction band edge of the employed Al0.43Ga0.57As confinement layer. The measurements further revealed a strongly enhanced luminescence efficiency of the quantum wells as compared to bulk material which is caused by the modified exciton transition probabilities due to carrier localization.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF00617615
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