Influences of group-III source preflow on the polarity, optical, and structural properties of GaN grown on nitridated sapphire substrates by metal-organic chemical vapor deposition.
In: Journal of Applied Physics, Jg. 117 (2015-03-28), Heft 12, S. 125305-1- (5S.)
Online
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Zugriff:
We report the influences of group-III source preflow, which were introduced prior to the growth of the low temperature GaN on the polarity, photoluminescence (PL), and crystallographic properties of GaN epilayers grown on nitridated c-plane sapphire substrates by metal-organic chemical vapor deposition. By studying the surface morphology evolutions under chemical etching in KOH, we found that with increasing the trimethyl-gallium (TMGa) preflow duration (t), the polarity of the GaN film can be changed from a complete N-polarity to a mixture of N-and Ga-polarity and further to a complete Ga-polarity. PL and high-resolution X-ray diffraction studies revealed that the impurity incorporation and the edge-and screw-type threading dislocations are strongly polarity dependent. A further study at the optimized t (i.e., 30 s for TMGa) shows that the polarity inversion of GaN can be realized not only by TMGa preflow but also by trimethyl-aluminium preflow and by trimethyl-indium preflow. A two-monolayer model was employed to explain the polarity inversion mechanism. [ABSTRACT FROM AUTHOR]
Titel: |
Influences of group-III source preflow on the polarity, optical, and structural properties of GaN grown on nitridated sapphire substrates by metal-organic chemical vapor deposition.
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Autor/in / Beteiligte Person: | Li, Chengguo ; Liu, Hongfei ; Chua, Jin |
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Zeitschrift: | Journal of Applied Physics, Jg. 117 (2015-03-28), Heft 12, S. 125305-1- (5S.) |
Veröffentlichung: | 2015 |
Medientyp: | academicJournal |
ISSN: | 0021-8979 (print) |
DOI: | 10.1063/1.4916243 |
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