THEORETICAL-ANALYSIS OF DISORDER EFFECTS ON ELECTRONIC AND OPTICAL-PROPERTIES IN INGAASP QUATERNARY ALLOY

The effects of structural and chemical disorder on electronic and opti cal properties of InGaAsP quaternary alloy are studied on the basis of a modified virtual crystal approximation calculated within a simple t ight-binding sp(3)s theory, which incorporates compositional disorder as an effective potential. Using a minimal set cf fitting parameters, me show that such an approach provides analytical results for calcula ting energy gaps and bowing parameters. We show that the calculated bo wing parameter agrees reasonably well with experimental data. The esse ntial features of structure and disorder-induced changes in electronic and optical structure are exhibited in the sp(3)s results by two cha racterization parameters: the subband energy spacings, and the density of states, The changes in each of them are found to depend on the int errelated trends of structure and disorder effects. (C) 1997 American Institute of Physics.