Systematic measurement of AlxGa1−xN refractive indices

Abstract

Dispersion of the ordinary and extraordinary indices of refraction have been measured systematically for wurtzitic AlxGa1−xN epitaxial layers with 0.0⩽x⩽1.0 throughout the visible wavelength region. The dispersion, measured by a prism coupling waveguide technique, is found to be well described by a Sellmeier relation. Discrepancies among previous measurements of refractive index dispersion, as a consequence of different growth conditions and corresponding band gap bowing parameter, are reconciled when the Sellmeier relation is parameterized not by x but by band gap energy.