Influence of the Ion Irradiation on the Properties of ß-FeSi₂ Layers Prepared by Ion Beam Assisted Deposition

ß-FeSi2 was 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
samples grow in a columnar way with pin-holes and their surface is rough.
A soft IBAD process with low Ar energy (EAr = 200 eV) and low Ar ion to
Fe atom ratio (IAr/AFe = 0.16) 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 EAr
and larger IAr/AFe. All samples are polycrystalline but with a pronounced
texture. The preferential orientation is also enhanced by the IBAD process.
The electrical properties of the layers were characterized by Hall effect
measurements and measurements of the I-V characteristics of simple diode
structures. The results are discussed in relation with the influence of
the ion beam.