Characterizing the thickness dependence of epitaxial GaN grown over GaN nanocolumns using X-ray diffraction
| Autor: | John D. Albrecht, Chih-Chung Yang, Yung-Sheng Chen, Tsung Yi Tang, K. L. Averett, Wen Yu Shiao |
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| Rok vydání: | 2008 |
| Předmět: |
Diffraction
Materials science Silicon business.industry chemistry.chemical_element Gallium nitride Condensed Matter Physics Epitaxy Inorganic Chemistry chemistry.chemical_compound Crystallography chemistry X-ray crystallography Materials Chemistry Optoelectronics Metalorganic vapour phase epitaxy Thin film business Molecular beam epitaxy |
| Zdroj: | Journal of Crystal Growth. 310:3159-3162 |
| ISSN: | 0022-0248 |
| DOI: | 10.1016/j.jcrysgro.2008.04.006 |
| Popis: | The crystal quality, as determined by X-ray diffraction, of GaN epitaxial films synthesized by MOCVD overgrowth of oriented GaN nanocolumns on Si(1 1 1) is studied as a function of film thickness and compared with control films grown on sapphire substrate. Samples were characterized using a three-beam X-ray diffraction technique from which depth-dependent rocking-curve widths (for the (0 1 1¯ 3)/(0 1¯ 12¯) crystal plane) are obtained as functions of depth. Through the examination of four samples prepared under conditions spanning key growth parameters it is found that optimizing for overgrowth at higher substrate temperatures can lead to coalesced films with significantly narrower rocking-curve widths. The results indicate that initially disconnected crystal domains stemming from individual columns do merge under the right conditions and that the coalesced crystal improves with increasing thickness. Overgrowth with the substrate temperature at 1000 °C (the highest of the study) resulted in a GaN overgrowth with properties superior to those of the control sample, a standard high-quality 2 μm MOCVD GaN thin-film grown on sapphire substrate. |
| Databáze: | OpenAIRE |
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