HUANG Hua-mao, YANG Guang, WANG Hong etc. Improvement of GaN Thin-film Quality Grown on Patterned Sapphire Substrate by High-temperature Pre-growth Treatment[J]. Chinese Journal of Luminescence, 2014,35(8): 980-985
HUANG Hua-mao, YANG Guang, WANG Hong etc. Improvement of GaN Thin-film Quality Grown on Patterned Sapphire Substrate by High-temperature Pre-growth Treatment[J]. Chinese Journal of Luminescence, 2014,35(8): 980-985 DOI: 10.3788/fgxb20143508.0980.
Improvement of GaN Thin-film Quality Grown on Patterned Sapphire Substrate by High-temperature Pre-growth Treatment
Before the epitaxy of low-temperature buffer layer
the patterned sapphire substrate was prepared by a pre-growth treatment at a high temperature under a small amount of trimethyl gallium (TMGa) and a great quantity of ammonia (NH
3
). Four types of blue light-emitting diode (LED) wafers were fabricated using different flow-rate of TMGa. The laser interferometer in MOCVD was used to monitor the thin-film reflectance during the epitaxial growth process. The high-resolution X-ray diffraction rocking curves of (002) and (102) crystal faces were utilized to estimate the threading dislocation density. The photoluminescence spectra were measured to feature the light-output performance. Moreover
LED chips were fabricated and tested. It is shown that the pre-growth treatment benefits the lateral growth of three-dimensional GaN islands in epitaxy process and leads to fast coalescence within a small thickness. Thus
the threading dislocation can be suppressed and the quality of epitaxial film would be improved. The enhancement of light-output power of LED chips can be up to 29.1% without degradation of electrical performance. However
the flow rate of TMGa should be tuned carefully
because excess quantity of TMGa would cause a large size of GaN grain crystal
which induces delayed coalescence time and low-quality of epitaxial film.
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references
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Related Institution
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