Electronic and Vibrational Properties of GeSn and SiGeSn Alloys

GeSn and SiGeSn alloys posses an intriguing
potential for IR optoelectronics and photovoltaic
applications. This book reports a detailed
compositional study of the electronic and
vibrational properties of GeSn and SiGeSn alloys.
The various optical transition energies in the
electronic band structure of the alloys are obtained
by spectroscopic ellipsometry and photoreflectance.
From the analysis, GeSn alloys are predicted to be a
direct gap material for Sn concentration as low as 6-
11 %. The bowing of optical transitions in GeSn and
SiGeSn alloys is found to scale with the atomic size
mismatch and electronegativity difference between
Si, Ge and -Sn. The Raman spectra of GeSn alloys
show two optical modes and two disorder-activated
modes. The Raman spectra of SiGeSn alloys are SiGe
like and the compositional dependence of vibrations
can be expressed in terms of the corresponding
vibrations in the binaries constituting the ternary
alloys. This experimental work should be useful to
scientists and engineers in the semiconductor field
and to anyone who is interested in learning the
basic optical properties of these novel materials.

Autorentext

Vijay R D'Costa received his Ph.D in Physics from Arizona State University(ASU).His research focuses on electronic and vibrational properties of semiconductor materials.He currently works as an Assistant Research Scientist in the Department of Physics,ASU.Prior to his Ph.D, he worked as a lecturer in physics at Chowgule College,Goa,India.

Klappentext

GeSn and SiGeSn alloys posses an intriguing potential for IR optoelectronics and photovoltaic applications. This book reports a detailed compositional study of the electronic and vibrational properties of GeSn and SiGeSn alloys. The various optical transition energies in the electronic band structure of the alloys are obtained by spectroscopic ellipsometry and photoreflectance. From the analysis, GeSn alloys are predicted to be a direct gap material for Sn concentration as low as 6-11 %. The bowing of optical transitions in GeSn and SiGeSn alloys is found to scale with the atomic size mismatch and electronegativity difference between Si, Ge and a-Sn. The Raman spectra of GeSn alloys show two optical modes and two disorder-activated modes. The Raman spectra of SiGeSn alloys are SiGe like and the compositional dependence of vibrations can be expressed in terms of the corresponding vibrations in the binaries constituting the ternary alloys. This experimental work should be useful to scientists and engineers in the semiconductor field and to anyone who is interested in learning the basic optical properties of these novel materials.