The Ge-C local mode in epitaxial GeC and Ge-rich GeSiC alloys

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The Raman signature of the local Ge-C mode for substitutional C is identified as a narrow line (8 cm-1 full width at half maximum) near 530 cm-1 in alloy films of Ge1-yCy(0≤y≤0.07) grown on Ge (100) substrates by low-temperature (200°C) molecular beam epitaxy. The intensity of the Ge-C line relative to the c-Ge line suggests that only a small fraction of the nominal C is in substitutional sites. In ternary alloys of Ge1-x-ySixCy with x=0.1 and 0.2 and y=0.03, the Ge-C mode disappears, suggesting a strong bias towards C bonding with Si as opposed to Ge. In Ge1-xSnx films the Ge-Sn mode is seen at 263cm-1. © 1998 American Institute of Physics.

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Applied Physics Letters