Improved refractive index formulas for the AlxGa1-xN and InyGa1-yN alloys

A detailed understanding of the nitride refractive indices is essential for the modeling and design of III-N laser structures. In this article, we rep ort on the assessment of the refractive index data available for the nitrid e alloys and present formulas for evaluating the refractive indices for var iations in both composition and photon energy. For AlxGa1-xN, an expression is given which fits well to experimental data below x <0.38, sufficient fo r the molefractions found in the cladding layers of III-N lasers. Due to th e almost complete lack of experimental refractive index data for InyGa1-yN, we propose an expression to give a first-order approximation for the refra ctive index. (C) 2001 American Institute of Physics.