GENERAL RELATION BETWEEN REFRACTIVE-INDEX AND ENERGY-GAP IN SEMICONDUCTORS

A review is given of existing relations and rules of thumb between refractive index and energy pp in semiconductors. An error deviation was calculated on more than one hundred materials. With only one set of fitting parameters, our model n2 = 1 + [A/(E(g) + B)]2, based on the classical oscillator theory, gives good fit except for IV-VI materials like PbS, PbSe, PbTe. The constant A was found to have the same value as the hydrogen ionization energy i.e. 13.6 eV and B = 3.4 eV.