Critical points of Si_1-yC_y and Si_1-x-yGe_xC_y layers strained pseudomorphically on Si(001)

verfasst von

W. Kissinger, H. J. Osten, M. Weidner, M. Eichler

Abstract

We investigate the influence of carbon on the optical transitions of Si_1-yC_y and Si_1-x-yGe_x:C_y layers grown pseudomorphically on a Si(001) substrate also including full strain compensation. The layers were investigated by spectroscopic ellipsometry and electroreflectance spectroscopy for carbon fractions y≤1.2 at. % and germanium fractions up to x=16 at. %. The spectra were analyzed by measuring and fitting electroreflectance spectra at 80 K and ellipsometry data at room temperature, resulting for both techniques in a weak and nearly linear dependence on the carbon fraction at all transitions. The results of both techniques are compared and discussed. The strong line broadening for increasing carbon fractions can be caused by a high scattering efficiency of the carbon. Our results indicate that the interpretation of optical spectra of carbon-containing alloys cannot be performed straightforwardly by simple interpolating between the appropriate band structures of silicon, germanium, and carbon. An analysis based on strain-induced contributions only also does not describe the experimental results correctly. For a complete description of the observed energy shifts detailed band structure calculations and further experimental data are necessary.

Externe Organisation(en)

Leibniz-Institut für innovative Mikroelektronik (IHP)

Typ

Artikel

Journal

Journal of applied physics

Band

79

Seiten

3016-3020

Anzahl der Seiten

5

ISSN

0021-8979

Publikationsdatum

15.03.1996

Publikationsstatus

Veröffentlicht

Peer-reviewed

Ja

ASJC Scopus Sachgebiete

Allgemeine Physik und Astronomie

Elektronische Version(en)

https://doi.org/10.1063/1.362705 (Zugang: Geschlossen)