Measurements of the Refractive Indices of MOCVD and HVPE Grown AlGAN Films Using Prism-Coupling Techniques Correlated With Spectroscopic Reflection/Transmission Analysis

Published

January 1, 2003

Author(s)

Norman Sanford, Larry Robins, Albert Davydov, Alexander J. Shapiro, Denis V. Tsvetkov, Vladimir A. Dmitriev, Stacia Keller, Umesh Mishra, Steven P. DenBaars

Abstract

Waveguide prism-coupling methods were used to measure the ordinary and extraordinary refractive indices of Al_xGaN films grown on sapphire substrates by HVPE and MOCVD. Several discrete wavelengths ranging from 442 nm to 1064 nm were used and the results were fit to one-term Sellmeier equations. The maximum standard uncertainty in the refractive index measurements was 1 0.005 and the maximum standard uncertainty in the self-consistent calculation for film thickness was 1 15 nm. Analysis of normal-incidence spectroscopic transmittance and reflectance measurements, correlated with the prism-coupling results, was used to determine the ordinary refractive index as a continuous function of wavelength from the band gap wavelength of each sample (between 252 nm and 364 nm) to 2500 nm. The Al compositions of the samples were determined using energy-dispersive X-ray spectroscopy analysis (EDS). HVPE grown samples had compositions x = 0.279, 0.363, 0.593, and 0.657. MOCVD samples had x = 0.00, 0.419, 0.507, 0.618, 0.660, and 0.666. The maximum standard uncertainty in the absolute EDS-determined value for x was 1 0.02.

Proceedings Title

Proc., Mater. Res. Soc. Symp.

Volume

743

Conference Dates

December 2-6, 2002

Conference Location

Boston, MA, USA

Pub Type

Conferences

Keywords

AlGaN, optical properties of semiconductors, refractive indices of GaN, wide bandgap semiconductors

Citation

Sanford, N. , Robins, L. , Davydov, A. , Shapiro, A. , Tsvetkov, D. , Dmitriev, V. , Keller, S. , Mishra, U. and DenBaars, S. (2003), Measurements of the Refractive Indices of MOCVD and HVPE Grown AlGAN Films Using Prism-Coupling Techniques Correlated With Spectroscopic Reflection/Transmission Analysis, Proc., Mater. Res. Soc. Symp., Boston, MA, USA (Accessed December 5, 2024)