Dielectric response of strained and relaxed Si{sub 1{minus}{ital x}{minus}{ital y}}Ge{sub {ital x}}C{sub {ital y}} alloys grown by molecular beam epitaxy on Si(001)
- Ames Laboratory (US-DOE) and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011 (United States)
- SiBond L.L.C., Hudson Valley Research Park, 1580 Route 52, Hopewell Junction, New York 12533-6531 (United States)
- Advanced Technology Materials, Commerce Drive, Danbury, Connecticut 06810 (United States)
- Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstr. 1, D-70569 Stuttgart (Germany)
Using spectroscopic ellipsometry, we measured the pseudodielectric function of Si{sub 1{minus}{ital x}{minus}{ital y}}Ge{sub {ital x}}C{sub {ital y}} alloys (0{le}{ital x}{le}0.48,0{le}{ital y}{le}0.05) grown on Si(001) using molecular beam epitaxy. For pseudomorphically strained layers, the energy shifts of the {ital E}{sub 1}, {ital E}{sub 1}+{Delta}{sub 1}, {ital E}{sub 0}{sup {prime}}, and {ital E}{sub 2} transitions are determined by line shape analysis and are due to alloy composition effects, as well as hydrostatic and shear strain. We developed expressions for hydrostatic and shear shift from continuum elasticity theory, using deformation potentials for Si and Ge, for biaxial stress parallel to the (001) growth plane in a diamond or zinc blende-type crystal and applied this to the ternary Si{endash}Ge{endash}C alloy. The energies of {ital E}{sub 1} and its spin-orbit split partner {ital E}{sub 1}+{Delta}{sub 1} agree fairly well with theory. The {ital E}{sub 2} transitions in Si{sub 1{minus}{ital x}}Ge{sub {ital x}} at around 4.3 eV depend linearly on Ge concentration. In case of relaxed layers, the {ital E}{sub 1} and {ital E}{sub 1}+{Delta}{sub 1} transitions are inhomogeneously broadened due to the influence of misfit and threading dislocations. For a silicon cap on top of a dislocated, relaxed SiGe layer, we recovered the bulk Si dielectric function. {copyright} {ital 1996 American Institute of Physics.}
- Research Organization:
- Ames National Laboratory
- DOE Contract Number:
- W-7405-ENG-82
- OSTI ID:
- 389019
- Journal Information:
- Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 8 Vol. 80; ISSN JAPIAU; ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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