Structural and optical properties of β-FeSi 2 film prepared by laser ablation method and comparison of β-FeSi 2 films prepared by three different methods

Abstract

Semiconductive iron disilicide (beta) -FeSi<SUB>2</SUB> is an attractive material for optoelectronic and thermoelectric devices that can be integrated on Si substrates. Advantages arise from the direct band-gap, high absorption coefficient and high thermoelectric power figure of merit. We present here the semiconductor properties of (beta) -FeSi<SUB>2</SUB> films on Si(100) substrate prepared by laser ablation (LA) method. We compare these results with those obtained from (beta) - FeSi<SUB>2</SUB> films prepared by ion beam synthesis using high- energy ion implantation and electron beam deposition methods. As for laser ablation, two independent growth processes were adopted using two different target materials, The first one was Fe deposition on Si (100) substrate by LA using Fe target and subsequent high-temperature annealing leading to solid phase epitaxy. The second was LA using (beta) -FeSi<SUB>2</SUB> bulk polycrystal as a target material which was grown by horizontal gradient freeze method. (beta) - FeSi<SUB>2</SUB> films prepared by the two processes were heat- treated as a function of annealing temperature and duration time. Structural characterizations were made by reflection high-energy electron diffraction, x-ray diffraction, Raman scattering and optical absorption spectroscopy measurements at room temperature, which revealed that high-quality semiconducting (beta) -FeSi<SUB>2</SUB> films can be fabricated by two LA processes.