Eur. Phys. J. Appl. Phys. 42, 99-102 (2008)
https://doi.org/10.1051/epjap:2008042

Strain effects of InP/Si and InP/porous Si studied by spectroscopic ellipsometry

¹ Laboratoire de Photovoltaïque et de Semiconducteurs, Centre de Recherche des Sciences et Technologies de l'Énergie, BP 95, Hammam-Lif 2050, Tunisia
² Laboratoire de Photonique et de Nanostructures, CNRS, Route de Nozay, 91460 Marcoussis, France

Corresponding author: Mohamed.lajnef@yahoo.fr

Received: 3 August 2007
Revised: 13 January 2008
Accepted: 5 February 2008
Published online: 28 March 2008

Abstract

In this work, we study the optical interband transitions of InP on silicon (InP/Si) and on porous silicon (InP/PSi) substrates grown by molecular beam epitaxy (MBE). Spectroscopic ellipsometry for photon energies from 2 to 5 eV is used to determine the InP/Si and InP/PSi complex refractive index and thickness. Bruggeman effective medium approximation (EMA) associated to the Cauchy model are used to model the experimental ellipsometric data. We have found that the E₁ and E₁ + transition energies of InP/Si and InP/PSi shift to low energies compared to bulk InP. This effect is interpreted as a result of the strain relaxation of the InP layers grown respectively on Si and porous Si substrates.