1. Key Laboratory of Interface Science and Engineering in Advanced Materials, Ministry of Education, Taiyuan University of Technology, Taiyuan 030024,China 2. Institute of Laser Engineering, Beijing University of Technology, Beijing 010100, China
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DOI:
10.7502/j.issn.1674-3962.2015.05.01
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Abstract:
The epitaxial growth of GaN-based film materials on the sapphire substrate was processed by metal organic chemical vapor deposition method. The structure of epitaxial wafers was designed and epitaxial growth conditions on single N-type GaN (N-GaN), multiple quantum well (MQW), electron blocking layer (P-AlGaN) and P-type GaN (P-GaN) material were optimized. The epitaxial wafers were characterized by X-ray diffraction (XRD), electroluminescence (EL), photoluminescence (PL). Results show that the optimized Si doped N-GaN and quantum barrier (QB) layer could lead better half peak width of (102), (002), voltage increases from 4.05 V to 3.84 V, 3.47 V, and luminous intensity increases from 5.68 mV to 6.08 mV. Then, Mg doped P-AlGaN layer was optimized, voltage reduces to 3.35 V and luminous intensity increases to 6.14 mV. Finally, The optimization of the growth temperature and annealing temperature on P-GaN layer make voltage increase from 3.35 V to 3.41 V, and luminous intensity increase to 6.75 mV. The voltage and the luminous intensity of chips were tested by automatic probe test under the test current of 20 mA. After optimization, the voltage decreases from 4.5 V to 3.8 V roughly, fell by 16%. Luminous intensity increases from 110 mcd to 135 mcd, increasing by 20% . Then, combining the experimental results and the theories, the influence of the N-GaN layer , Si doped QB layer, Mg doped P-AlGaN layer, and the growth temperature and activation temperature of P-GaN layer on the voltage and brightness were analyzed. These results may provide a better experiment guidance and theoretical support for the growth of high quality GaN epitaxial thin film materials and the optimization of high performance LED device.