Optical transitions in strained Si_1-yC_y and Si_1-x-yGe_xC_y layers on Si(001)

verfasst von

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

Abstract

The addition of carbon atoms into Si or SiGe layers on Si opens the possibility for strain and bandstructure engineering. In this paper we will investigate the influence of carbon on the optical transitions of Si_1-yC_y and Si_1-x-yGe_xC_y layers grown pseudomorphically on Si(001) substrate using solid source MBE including also full strain-compensation. The layers were investigated by spectroscopic ellipsometry and electroreflectance spectroscopy for y ≤ 1.2%. From the numerical derivatives of the measured dielectric constants, we determined the critical points energies E₀′, E₁ and E₂ as a function of the carbon content y. This shift was analyzed by measuring and fitting electroreflectance spectra at 80K and ellipsometry data at room temperature, resulting in a week and nearly linear dependence on the carbon content at all transitions. These dependencies indicate that the interpretation of optical spectra of C-containing alloys can not be performed straightforward by simple interpolating between the appropriate band structures of silicon, germanium and carbon. An analysis based on only strain-induced contributions also does not describe the experimental results correctly. For a description of the observed energy shifts for pseudomorphic Si_1-x-yGe_xC_y we have to consider at least strain-induced effects and effects due to alloying.

Externe Organisation(en)

Leibniz-Institut für innovative Mikroelektronik (IHP)

Typ

Konferenzaufsatz in Fachzeitschrift

Journal

Materials Research Society Symposium - Proceedings

Band

379

Seiten

199-204

Anzahl der Seiten

6

ISSN

0272-9172

Publikationsdatum

1995

Publikationsstatus

Veröffentlicht

Peer-reviewed

Ja

ASJC Scopus Sachgebiete

Allgemeine Materialwissenschaften, Physik der kondensierten Materie, Werkstoffmechanik, Maschinenbau