| Autor: |
Todd, M., McMurran, J., Kouvetakis, J., Smith, D. J. |
| Zdroj: |
Chemistry of Materials; October 15, 1996, Vol. 8 Issue: 10 p2491-2498, 8p |
| Abstrakt: |
High-quality diamond-structured Ge1-xCx alloys have been grown on (100) Si using ultrahigh-vacuum chemical vapor deposition techniques and novel chemical precursors. Two-dimensional growth of single-crystal heteroepitaxial layers (30−120 nm thick) of germanium−carbon alloys with carbon concentrations up to 7% has been achieved by reactions of GeH4 with germylmethanes, (GeH3)4-xCHx (x = 1−3), at 470 °C. The composition of the materials was established by extensive Rutherford backscattering (RBS) carbon resonance analysis, and the layer crystallinity was characterized by cross-sectional transmission electron microscopy and RBS channeling experiments. RBS ion channeling revealed that the carbon primarily occupied substitutional sites in the diamond-like Ge lattice. Alloys with low carbon content displayed virtually perfect crystallinity whereas materials with high carbon incorporation had structural defects in the form of {111} stacking faults and microtwins. The thin film microstructure of a given alloy composition was independent of the precursor, but the efficiency of carbon incorporation increased dramatically as the number of GeH3 moieties in the precursor increased. Further characterization by Auger electron spectroscopy and secondary ion mass spectrometry showed that the materials were pure and highly homogeneous, and electron energy loss spectroscopy indicated sp3 hybridized diamond-like carbon. The synthesis and characterization of novel (trihalogermyl)methane compounds such as (Br3Ge)3CH and (Cl2XGe)2CH2 (X = Cl, Br, or I) and their reactions with LiAlH4 to produce the corresponding hydrides is also reported. |
| Databáze: |
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