Excited States of Bound Exciton Complexes in CdS

The excited states of bound exciton complexes have been studied in CdS, and information relating to donor impurities in this material has been deduced. Donor ionization energies of 0.026 eV were calculated; this value gives a good fit to the experimentally determined ionization energies of the I₅ and I2c neutral donors. A good theoretical fit to the $n=2$ magnetic-field-split levels is obtained, using Wheeler and Dim-mock's model. The fit to the $n=3$ states is not as good. This is most likely due to the mixing of high-quantum-number states of different principle quantum numbers through the diamagnetic operator of the Hamiltonian.