Photoionization of deep impurity centers in quantum well structures

The absorption of light by photoionization of deep impurity centers in quan tum well heterostructures is studied theoretically using a model with a max imally localized potential. Analytic expressions are found for the photoion ization cross sections for light polarized perpendicular and parallel to th e axis of the structure, disregarding the effect of the impurity potential on the continuum electronic states. The dependence of the frequency variati on of the cross section on the charge state of the impurity after photoioni zation, as well as on the position of the impurity in the structure and the doping profile, is studied qualitatively near the absorption threshold. (C ) 1999 American Institute of Physics. [S1063-7826(99)01504-5].