Effects of H2/NH3 flow-rate ratio on the luminescent, structural, and electrical properties of GaN epitaxial layers grown by MOCVD |
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| Authors: | Chien-Cheng Yang Pao-Ling Koh Meng-Chyi Wu Chih-hao Lee Gou-Chung Chi |
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| Affiliation: | (1) Department of Electrical Engineering, National Tsing Hua University, 300 Hsinchu, Taiwan, ROC;(2) Opto-Electronics and Systems Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan, ROC;(3) Department of Physics, National Central University, 320 Chung-Li, Taiwan, ROC;(4) Department of Engineering and System Science, National Tsing Hua University, 300 Hsinchu, Taiwan, ROC |
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| Abstract: | GaN epitaxial layers were grown on sapphire substrates in a separate-flow reactor by metalorganic chemical vapor deposition.
The flow-rate ratio of H2 on the upper stream to NH3 on the bottom stream is varied from 0.5 to 2. The growth condition and characterization of the GaN epitaxial layers are investigated
in detail. The H2 flow rate of the upper stream strongly affects the reactant gas flow pattern near the substrate surface and thus influences
the quality of epitaxial layers. At the optimum H2/NH3 flow ratio of 1.0, we can obtain a good quality of GaN epitaxial layers which exhibit a strong near band-edge emis-sion in
the 20 K photoluminescence (PL), a full width at half maximum of 66 meV for the 300 K PL, an electron mobility of 266 cm2/V-s and concentration of 1 × 1018 cm−3 at 300 K. |
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| Keywords: | GaN high band-gap energy photoluminescence (PL) x-ray diffraction (DC-XRD) |
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