X–Γ indirect intersubband transitions in type II GaAs/AlAs superlattices

Abstract

Fouriertransform infrared and Raman spectroscopies of plasmon anisotropy in heavily doped GaAs/AlAs superlattices J.

Quantum tailoring of optical transitions in InxGa1−xAs/AlAs strained quantum wells

“…Experimental evidence of mid-infrared X -⌫ intersubband transitions were recently reported in short-period GaAs/AlAs ͑001͒ superlattices. 14 Figure 2͑a͒ displays the calculated band diagram for the ͑In 0.3 Ga 0.7 As͒5 ML/͑AlAs͒ QW. Figure 2͑b͒ shows the observed interband luminescence at Tϭ4.2 K ͑right panel͒ and room-temperature intersubband absorption for z-polarized incident light ͑left panel͒.…”

Spatially Indirect Emission in a Luminescent Nanocrystal Molecule

“…Similar behavior has been observed previously in type-II nanocrystal heterostructures in the form of charge-transfer emission. − The probability of spatially indirect radiative recombination will increase with increasing CdS arm length. Because spatially indirect transitions are slower relative to the rate of direct transitions, increasing the incident photon flux may saturate the indirect channel before the direct channel, resulting in a reduction of the relative yield of indirect transitions. , Temperature also plays a role in the propensity for the indirect transition: thermal energy at room temperature allows a non-negligible population of electrons in a CdS-dominant excited state, increasing the probability of a spatially indirect emission, regardless of the spatial origin of the carrier.…”

1.26 μm intersubband transitions in In0.3Ga0.7As/AlAs quantum wells

“…It must be noted that this selection rule is peculiar to our system; in short-period type II superlattices, for instance, where the X state is quantum confined and therefore the wave function overlap is larger, the X -⌫ intersubband transition is basically polarization insensitive. 17 The energy-level diagram of the heterostructure as derived within our TB approximation is shown in the inset of Fig. 3.…”