THE BINDING-ENERGY OF AN EXCITON IN TYPE-II QUANTUM-WELLS WITH A DIELECTRIC MISMATCH

From a general viewpoint, the binding energy of the excitons in type-I I hetero-quantum-wells with the presence of a dielectric mismatch is d iscussed by making use of image potentials, variational method and inf inite-potential-barrier model. The calculation is performed for variou s parameters including the electron-hole mass ratio sigma, dielectric constant ratio delta and well width d. A static Gabovish-type potentia l is engaged to describe the image potential inside the well. It is fo und that the image potential may play an important role in the formati on of the excitons. The contribution of image potentials to the bindin g energy is compared with binding energy for two kinds of type-II hete ro-QWs, GaSb-InAs-GaSb and AlAs-GaAs-AlAs. In these two cases, the ima ge potentials are above 10% of the corresponding binding energies.