Wannier-Stark Quantization and Bloch Oscillator in Biased Semiconductor Superlattices
We review salient features exhibited by electronic states in semiconductor superlattices subjected to a static electric field applied parallel to the growth axis. When the field is large enough the band structure is destroyed and replaced by evenly spaced levels: the Wannier-Stark ladder. The Wannier-Stark ladders are calculated to survive the broadening due to static scatterers (ionized impurities, interface defects). We briefly compare the average spatial localization of the Wannier-Stark states to their semiclassical counterpart derived from the Bloch oscillator formalism.We show that the field-induced quantization leads to an effective blue shift of the band-to-band absorption edge as well as to the existence of oscillatory structures which are periodic in 1/F.
KeywordsLandau Level Interface Defect Static Scatterer Bloch Oscillator Semiconductor Superlattices
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