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-ra nge impurity potential model. It is demonstrated that, if the well is suffi ciently thin, an effect of positional disorder exists: the binding energy o f a deep-level impurity center is a decreasing function of the center trans verse coordinate. It is found that the positional disorder effect is enhanc ed in the parabolic potential well in comparison with the rectangular well of finite depth. The spectral dependence of the photoionization cross secti on of deep-level impurity centers is examined. It is shown that the spectra l 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. (C) 2000 MAIK "Nauka/ Interperiodi ca".