Feaftures of the double photoionization spectra of two-electron impurity centers in quasi-zero-dimensional structures

The zero-range potential method has been generalized to the case of two-electron impurity centers with an effective nuclear charge equal to zero in a spherically symmetric quantum dot (QD), and on the basis of this method the first ionization potential has been calculated by variational method. It is shown that as the radius of QD decreases, the threshold value of the second ionization potential also decreases, beginning with which the existence of the two-electron bound state is possible due to an increase in the size-quantization energy accompanied by suppression of mutual electron repulsion. The light impurity absorption coefficient has been calculated using the dipole approximation for double ionization of the two- electron impurity center by a single photon in a quasi-zero-dimensional structure, which is the transparent dielectric matrix with semiconductor QDs synthesized in it. It is shown that characteristic feature of the double photoionization spectrum is a two-humped profile of the spectral curve due to electron correlations.