On the theory of photoionization of deep-level impurity centers in a parabolic quantum well

The localized state of a deep-level impurity in a quantum well (QW) with a parabolic potential profile is investigated within the context of a zero-range impurity potential model. It is demonstrated that, if the well is sufficiently thin, an effect of positional disorder exists: the binding energy of a deep-level impurity center is a decreasing function of the center transverse coordinate. It is found that the positional disorder effect is enhanced in the parabolic potential well in comparison with the rectangular well of finite depth. The spectral dependence of the photoionization cross section of deep-level impurity centers is examined. It is shown that the spectral dependence of the photoionization cross section is not monotonic, and the position of the impurity-absorption edge depends strongly on the impurity center coordinate and the QW parameters.