17 April 2000 Effects of buffer layer growth conditions on the GaN epilayer quality by MOCVD
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Proceedings Volume 3938, Light-Emitting Diodes: Research, Manufacturing, and Applications IV; (2000) https://doi.org/10.1117/12.382833
Event: Symposium on Integrated Optoelectronics, 2000, San Jose, CA, United States
Abstract
We have found that the electrical and optical properties of GaN epilayers strongly depend on buffer TMGa flow rates and NH3 flow rates. At low flow rate of 4 sccm, the buffer layer quality was good so the concentrations of undoped GaN epilayers decreased and a stronger band-edge emission of 362 nm can be observed in photoluminescence spectra. The carrier density of the films can be reduced from 1018 to 1017 cm-3 by increasing the NH3 flow rate from 0.5 up to 1 SLM and comparatively increased the near-band-edge emission. So, with a NH3 flow rate as high as 1 SLM, the GaN epilayers with good optical quality can be obtained. The excitation power density of He-Cd laser influences the photoluminescence property of GaN epilayers. At high excitation power density of 637 W/cm2, the near-band-edge luminescence (362 nm) is dominant and the deep level luminescence (near 550 nm) appears very weak. But at low excitation power density, the luminescence from defect yellow band levels is stronger than the near-band-edge transitions.
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Fuh-Shyang Juang, Yan-Kuin Su, Shoou-Jinn Chang, T. K. Chu, C. S. Chen, L. W. Chi, Kin Tak Lam, "Effects of buffer layer growth conditions on the GaN epilayer quality by MOCVD", Proc. SPIE 3938, Light-Emitting Diodes: Research, Manufacturing, and Applications IV, (17 April 2000); doi: 10.1117/12.382833; https://doi.org/10.1117/12.382833
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