TIGHT-BINDING CALCULATION OF ZNSE/GE SUPERLATTICES - ELECTRONIC-STRUCTURE AND OPTICAL PROPERTY

The results of a detailed tight-binding calculation of the electronic structure and optical properties of (ZnSe)(n)/(Ge-2)(m) (110) superlattices are presented for a wide range of n,m less than or equal to 20. It is found that the fundamental energy gap increases with decreasing superlattice period due to spatial quantum confinement effects. For all reasonable values (ranging from 0.2 to 2.0 eV) of the valence band discontinuity used in the calculation, no interface states are found in the thermal gap of the (ZnSe)(n)/(Ge-2)(m) (110) (n,m less than or equal to 20) system. An indirect-direct band gap transition is found to be driven by increasing valence band offset. The optical properties of the superlattices are investigated by calculating the absorption coefficient. The results are analyzed according to the calculated electronic structure and compared with those of the corresponding bulk materials. (C) 1995 American Institute of Physics.