Transport, optical and thermoelectrical properties of Cr and Fe disilicides and their alloys on Si(1 1 1)

Transport, optical and thermopower properties of thin epitaxial CrSi2 and β-FeSi2 films and their alloys (10–100 nm thick) on Si(1 1 1) p-type substrates have been investigated. Ex situ temperature Hall measurements of thin silicide films on Si(1 1 1) p-type substrate with 10 Ω cm resistivity have shown that only at room and low temperatures the shunting effect of the substrate can be accounted within the two-layer model of semiconductor layers connected in parallel. It has been shown that in β-FeSi2 films, grown on Si(1 1 1) by template technology, the majority carriers are the electrons with high mobility. Template growth technology for alloy silicide films has been offered based on deposition of Cr and Fe with different deposition rates on hot silicon substrate. As-grown alloy films display semiconductor type optical absorption, but only Fe0.9Cr0.1Si2 film keeps the crystalline structure of β-FeSi2. It has been shown that the iron disilicide, doped by chromium atoms, displays the semiconductor properties with direct band gap of about 0.6 eV. The majority carriers in the both alloy silicide films are holes from Hall effect and thermopower measurements.