SemiconductingMg2Si thin films prepared by molecular-beam epitaxy
| Autor: | James Becker, André Vantomme, Guido Langouche, John E. Mahan |
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| Rok vydání: | 1996 |
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| Zdroj: | Physical Review B. 54:16965-16971 |
| ISSN: | 1095-3795 0163-1829 |
| DOI: | 10.1103/physrevb.54.16965 |
| Popis: | ${\mathrm{Mg}}_{2}$Si is a semiconductor with a band gap previously reported to be in the range 0.6--0.8 eV. In spite of potential optoelectronic applications in an important infrared range, the growth of ${\mathrm{Mg}}_{2}$Si thin films on silicon substrates has received scant attention. This may be due to the difficulty of preparing ${\mathrm{Mg}}_{2}$Si in thin-film form. We find that intended reactive deposition of magnesium onto a silicon substrate, at temperatures from 200 to 500 \ifmmode^\circ\else\textdegree\fi{}C, results in no accumulation of magnesium. However, codeposition of magnesium with silicon at 200\ifmmode^\circ\else\textdegree\fi{}C, using a magnesium-rich flux ratio, gives a stoichiometric ${\mathrm{Mg}}_{2}$Si film. The amount of magnesium which accumulates is determined by the total amount of silicon which was codeposited; the excess magnesium in the flux does not condense. Measurements of the optical transmittance of thin films thus obtained reveal an absorption edge. Extraction of the absorption coefficient from the data, and analysis of its energy dependence, suggest an indirect band gap of \ensuremath{\sim}0.74 eV, plus direct transitions at \ensuremath{\sim}0.83 and \ensuremath{\sim}0.99 eV. \textcopyright{} 1996 The American Physical Society. |
| Databáze: | OpenAIRE |
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