High-field Franz-Keldysh effect and exciton ionization in semiconductor quantum wires

We investigate the Franz-Keldysh effect and exciton ionization in semicondu ctor quantum wires, Absorption spectra are calculated near the band gap by solution of the low-density semiconductor Bloch equations in real space. Th e Sommerfeld factor and field-induced tunnel ionization of the exciton sign ificantly affect the continuum portion of the absorption spectrum and remov e the well known divergence problem associated with the 1D density of state s at all field strengths. For reasonable electric field strengths substanti al and tunable absorption oscillations appear above the band gap. Moreover, Tor very large fields, transparency can be achieved in the continuum for c ertain spectral positions.