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) superlat tices 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 al l reasonable values (ranging from 0.2 to 2.0 eV) of the valence band d iscontinuity 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 eq ual 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 coef ficient. The results are analyzed according to the calculated electron ic structure and compared with those of the corresponding bulk materia ls. (C) 1995 American Institute of Physics.