LO-phonon-induced screening of electron–electron interaction in D−centres and quantum dots

A problem of screening of electron–electron interaction by LO phonons is investigated for bound two-electron systems in bulk semiconductors and semiconductor quantum dots. We consider a D − centre and a two-electron quantum dot and obtain the effective LO-phonon-induced interaction between the electrons, i.e., V eff ( r 12 )∼ e 2 /[ε eff ( r 12 ) r 12 ], where r 12 is the interelectron distance and ε eff ( r 12 ) is the effective phonon dielectric function. The calculated phonon dielectric function rapidly increases for small r 12 starting from the high-frequency dielectric constant, , and reaches some constant value, , at relatively small interelectron distances. We have found that—in most cases— is less than the static dielectric constant, ε s . Only in the weakly ionic compounds, like GaAs, . We argue that—in the bound few-electron systems— better approximates the average LO-phonon-induced screening than the commonly used ε s . We have also shown that the coupling with LO phonons leads to the increase of the binding energy of the two-electron system confined in the quantum dot.