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Ellipsometry Studies, Optical Properties, And Band Structure of Gel.1-yCy, Ge-RICH Si1-x-yGexCy, And Boron-Doped Si1-xGexAlloys

Published online by Cambridge University Press:  10 February 2011

Kelly E. Junge ,
Ruidiger Lange ,
Jennifer M. Dolan ,
Stefan Zollner ,
Josef Humlfcek ,
M. W. Dashiell ,
D. A. Hits ,
B. A. Orner  and
James Kolodzey
Kelly E. Junge
Affiliation:
Ames Laboratory and Dept. of Physics and Astronomy, Iowa State University, Ames, IA 50011
Ruidiger Lange
Affiliation:
Ames Laboratory and Dept. of Physics and Astronomy, Iowa State University, Ames, IA 50011
Jennifer M. Dolan
Affiliation:
Ames Laboratory and Dept. of Physics and Astronomy, Iowa State University, Ames, IA 50011
Stefan Zollner
Affiliation:
Motorola Semiconductor Technology, Arizona Technology Laboratories, Technology Test and Analysis Laboratory, MD M360, 2200 West Broadway Road, Mesa, AZ 85202
Josef Humlfcek
Affiliation:
Department of Solid State Physics, Faculty of Science, Masaryk University, Kotldrskd 2, 61137 Brno, Czech Republic
M. W. Dashiell
Affiliation:
Department of Electrical and Computer Engineering, 140 Evans Hall, University of Delaware, Newark, DE 19716
D. A. Hits
Affiliation:
Department of Electrical and Computer Engineering, 140 Evans Hall, University of Delaware, Newark, DE 19716
B. A. Orner
Affiliation:
Department of Electrical and Computer Engineering, 140 Evans Hall, University of Delaware, Newark, DE 19716
James Kolodzey
Affiliation:
Department of Electrical and Computer Engineering, 140 Evans Hall, University of Delaware, Newark, DE 19716
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Abstract

We measured the pseudodielectric function (PDF) of Ge1-yCy and Ge-rich Si1-x-yGexCy alloys from 1.1 to 5.2 eV using spectroscopic ellipsometry. These alloys were grown by molecular beam epitaxy at 6000C on (001) Si substrates. Analytical lineshapes fitted to numerically calculated derivatives of their PDFs determined the critical-point parameters of the E1, E1+Δ1, E0', and E2 transitions. The critical-point energies of the Ge1-yCy alloys were found to be similar to bulk Ge. This indicates that the presence of C in these alloys only has a small influence on the band structure. For some samples, the amplitude of the PDF is much lower than in bulk Ge, which can be attributed to surface roughness and explained within the framework of the Kirchhoff theory of diffraction or using effective medium theory. The degree of surface roughness indicated by optical measurements was confirmed by atomic force microscopy. We also studied bulk Czochralski-grown Si1-xGex alloys (0<x<0.28) doped with boron. Due to doping, the critical points shift to lower energies as reported previously for bulk Si and Ge.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 533: Symposium FF – Epitaxy & Applications of Si-Based Heterostructures , 1998 , 125
Copyright
Copyright © Materials Research Society 1998

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