Zero-dimensional characteristic of the trion absorption in a modulation-doped CdTe quantum well at high depletion

The electron concentration in a modulation-doped CdTe quantum well is reduc ed by applying reverse bias to a transparent Schottky electrode on the samp le surface. The absorption associated with creation of the excitonic trion then appears to have zero-dimensional properties rather than the usual 2D p roperties. This suggests that, at high depletion, electrons become localise d laterally in the electric potential fluctuations produced by the large nu mber of positively charged donors in the doping plane situated close to the well edge.