EXCITONIC MOLECULE IN WURTZITE CRYSTALS

We calculate with the variational technique the fine structure of a bi exciton in wurtzite crystals with the effective electron-hole exchange interaction taken into account. The values of the electron-hole excha nge integrals are taken from the free exciton GAMMA5-GAMMA6 splitting. We calculate the biexciton dissociation energy and the ratio of mixin g of the symmetric and antisymmetric envelopes which arises from the e lectron-hole exchange interaction. Results are presented for CdS, CdSe and ZnS crystals.