SPECTROSCOPIC ELLIPSOMETRY CHARACTERIZATION OF (INGA)N ON GAN

Pseudodielectric function spectra of hexagonal (InGa)N epitaxial layer s on GaN were obtained by spectroscopic ellipsometry and compared with photoreflection spectra. Composition and thickness of the InxGa1-xN l ayers grown by metalorganic chemical vapor deposition, were varied bet ween 0.04 less than or equal to x less than or equal to 0.10 and 15-60 nm, respectively. The pseudodielectric function exhibits a clear maxi mum at the fundamental gap energy of the (InGa)N, which allows a deter mination of the In content via the composition dependence of that gap energy. The pseudodielectric function spectrum of a complete GaN/(InGa )N/(AlCa)N/GaN light-emitting diode structure shows maxima arising fro m fundamental gap interband transitions of all constituent layers incl uding the (InGa)N active region, (C) 1998 American Institute of Physic s.