Binding energy of ionized-donor-bound excitons in two-dimensional semiconductors

The ground-state energies of the two-dimensional ionized-donor-bound exciton ($D^{+}$,X) have been calculated variationally for all values of the effective electron-to-hole mass ratio σ. They are compared with those obtained in the three-dimensional case using the same 55-term wave function. We found that in the two-dimensional case the ($D^{+}$,X) complex remains stable until σ=0.88, which is about two times larger than the value obtained in the three-dimensional case.