Diffusion of oxygen in bulk GaN crystals at high temperature and at high pressure
| Autor: | Andrii Nikolenko, O. Belyaev, Vladimir Z. Turkevich, V. B. Kapustianyk, В. Tsykaniuk, Igor Dzięcielewski, Izabella Grzegory, J.L. Weyher, S. Porowski, Martin Albrecht, Marcin Sarzyński, B. Sadovyi, I. A. Petrusha, V. V. Strelchuk |
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| Rok vydání: | 2016 |
| Předmět: |
010302 applied physics
Free electron model Materials science Annealing (metallurgy) Analytical chemistry chemistry.chemical_element Halide 02 engineering and technology 021001 nanoscience & nanotechnology Condensed Matter Physics Epitaxy 01 natural sciences Nitrogen Oxygen Inorganic Chemistry chemistry 0103 physical sciences Materials Chemistry Limiting oxygen concentration 0210 nano-technology Spectroscopy |
| Zdroj: | Journal of Crystal Growth. 449:35-42 |
| ISSN: | 0022-0248 |
| DOI: | 10.1016/j.jcrysgro.2016.05.037 |
| Popis: | Experimental studies of diffusion of oxygen in bulk wurtzite-type GaN crystals grown by Halide Vapor Phase Epitaxy (HVPE) are reported. Oxygen concentration profiles were studied in as-grown GaN crystals and also after annealing of crystals at temperatures up to 3400 K and pressures up to 9 GPa. Investigated crystals contained large conical defects i.e. pinholes of significantly higher oxygen concentration ( N O =(2–4)×1019 cm −3 ) than that in the bulk matrix ( N O −3 ). The pinholes were revealed by a photo-etching method in as-grown and annealed GaN samples. Confocal micro-Raman spectroscopy was applied to measure the profiles of free electron concentration, which directly corresponds to the concentration of oxygen impurity. Lateral scanning across the interfaces between pinholes and matrix in the as-grown HVPE GaN crystals showed sharp step-like carrier concentration profiles. Annealing at high temperature and high pressure resulted in the diffusion blurring of the profiles. Analysis of obtained data allowed for the first time for estimation of oxygen diffusion coefficients D O ( T , P ). The obtained values of D O ( T , P ) are anomalously small similarly to the values obtained by Harafuji et al. by molecular dynamic calculations for self-diffusion of nitrogen. Whereas oxygen and nitrogen are on the same sublattice it could explain the similarity of their diffusion coefficients. |
| Databáze: | OpenAIRE |
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