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HL: Fachverband Halbleiterphysik

HL 62: Gallium Nitride: Optical and Electronic Properties

HL 62.11: Talk

Wednesday, March 9, 2016, 17:45–18:00, H17

Analysis of in-situ reflectance measurements during growth of AlInN/GaN Bragg reflectors — •Christoph Berger, Armin Dadgar, Jürgen Bläsing, and André Strittmatter — Otto-von-Guericke-Universität Magdeburg

We present in-situ analysis of lattice-matched AlInN/GaN distributed Bragg reflectors. For a comprehensive analysis of the in-situ reflectance monitored at three different wavelengths (405 nm, 633 nm, 950 nm), we first determined the optical constants of AlInN at high (growth) temperature. Therefore, we have grown single AlInN layers on a thick GaN-on-sapphire buffer structure. Fitting the resulting in-situ transients, allowed us to extract the refractive index and extinction coefficient at growth temperature. In combination with the optical properties of AlInN determined at room temperature, we were able to interpolate a temperature dependent dispersion for lattice-matched AlInN. With these data, the complex reflectance transients were simulated with very good agreement. From these simulations, growth rates and the resulting layer thickness were determined and even small growth rate fluctuations could be detected. In addition, the optical characteristic of the final DBR structure has been predicted already from the in-situ measurement. Simulations from high-resolution X-ray diffraction scans agree very well with the results from in-situ analysis.