Influence of the ion irradiation on the properties of β-FeSi 2 layers prepared by ion beam assisted deposition

Abstract

β-FeSi 2 layers on Si substrates were produced by ion beam assisted deposition (IBAD). The influence of the deposition parameters on the structure was studied by Rutherford backscattering, X-ray diffraction, cross-section transmission electron microscopy, and scanning electron microscopy. The layers grow in a columnar way with pin-holes and their surface is rough. An IBAD process with low Ar energy ( E Ar = 200 eV) and low Ar ion to Fe atom ratio ( I Ar A Fe = 0.15 ) improves the layer structure in comparison to samples prepared without Ar irradiation. Less pin-holes are formed, and the roughness shows a minimum. The roughness increases for larger values of E Ar or I Ar A Fe . All samples are polycrystalline but with a pronounced texture. The preferential orientation FeSi 2(110,101)∥Si(001), with a few degrees misorientation, is found. This preferred grain orientation is also enhanced by the IBAD process. Hall effect measurements were done and the I–V characteristics of the samples were measured. The results are discussed in relation with the influence of the ion beam.