Comment on 'Low-temperature homoepitaxial growth on high-miscut Si(111) mediated by thin overlayers of Pb' [Appl. Phys. Lett. 75, 2954 (1999)]
| Autor: | Paul G. Evans, Frans Spaepen, John Chervinsky, Oscar D. Dubon, Jene Andrew Golovchenko |
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| Rok vydání: | 2000 |
| Předmět: | |
| Zdroj: | Applied Physics Letters. 77:2616-2616 |
| ISSN: | 1077-3118 0003-6951 |
| DOI: | 10.1063/1.1318930 |
| Popis: | Wei and Su recently published a letter in this journal on low-temperature homoepitaxial growth of silicon mediated by thin overlayers of Pb. A significant portion of the experimental work reported in their letter was performed in our laboratory ~depositions, Rutherford backscattering analysis, and electron microscopy!. Those experiments were poorly controlled and produced major inconsistencies that made the work unfit for publication. A subsequent, more systematic, investigation revealed the origin of these inconsistencies and established the precise conditions for high-quality growth. Our report on the latter work appeared in this journal several months prior to submission of Ref. 1. The purpose of this comment is to correct the factual errors reported in Ref. 1. Foremost among these is the claim that high-quality Si films can be grown on vicinal Si~111! for Pb coverages of 0.8–1.0 ML (1 ML57.83310 atoms cm) by first depositing the Pb overlayer and subsequently growing the Si film without continuously supplying the sample surface with additional Pb. As reported in Ref. 2, the growth of arbitrarily thick, high-quality Si films requires a Pb coverage of 1.0 60.1 ML which cannot be achieved under the conditions outlined in Ref. 1 because Pb desorbs from the surface of the growing film. We have observed evaporation of Pb from vicinal surfaces including those from the same substrate material used by Wei while working in our laboratory. To maintain a constant Pb coverage at substrate temperatures of 280 °C or higher, one must deposit Pb during the growth of the Si film. For example, at 295 °C a Pb flux of 0.12 ML min is needed to maintain a Pb coverage of 1.0 ML on the sample surface. The Pb coverages reported in Ref. 1 were measured at the end of the deposition of Si. By wrongly assuming that the final Pb coverages they measured represent the actual coverages during growth, Wei and Su have overlooked the effect of Pb desorption on their results. The misinterpretation of ion channeling spectra in Ref. 1 undermines the authors’ claim that high-quality films can be |
| Databáze: | OpenAIRE |
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