0000000000609392
AUTHOR
B. Chastaingt
Type II narrow double barrier quantum well structures : Γ-X coupling and interface effects
Photoluminescence (PL), PL excitation and time resolved PL experiments have been performed on Al0.42Ga0.58As/AlAs/GaAs symmetric double barrier quantum wells (DBQW) with only one or two AlAs monolayers constituting the intermediate barriers. In agreement with the envelope function predictions we show that such DBQW's undergo a type I - type II transition when the GaAs thickness is reduced below 7 and 5 monolayers for 2 and 1 AlAs molecular planes respectively. In type II configuration the PL decay time is found to be strongly dependent on the energy difference between AlAs Xz - and GaAs Γ - electron confined states and the coupling parameter of the Γ and Xz valleys can be deduced (4.2 meV o…
Controlled type-I–type-II transition in GaAs/AlAs/AlxGa1−xAs double-barrier quantum wells
We show that the insertion of extremely narrow AlAs layers in double-barrier GaAs/AlAs/${\mathrm{Al}}_{\mathrm{x}}$${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$As quantum wells results in a variety of electronic configurations, thus providing a powerful tool for tailoring the electronic transitions in GaAs heterostructures. In particular, the transition from type-I to type-II recombination is shown to occur in correspondence with variations by a single monolayer in the thickness of the AlAs and/or GaAs layers. Drastic changes in the recombination lifetimes are correspondingly observed; at the same time, the photoluminescence efficiency is found to be almost independent of the type-I-…