Transport, optical and thermoelectrical properties of Cr and Fe disilicides and their alloys on Si(111)

Transport, optical and thermopower properties of thin epitaxial CrSi2 and b eta -FeSi2 films and their alloys (10-100 nm thick) on Si(1 1 1) p-type sub strates have been investigated. Ex situ temperature Hall measurements of th in silicide films on Si(1 1 1) p-type substrate with 10 Omega cm resistivit y 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 beta -FeSi2 films. grown on Si(1 1 1)by template technology, the majority carriers are the ele ctrons with high mobility. Template growth technology for alloy silicide fi lms has been offered based on deposition of Cr and Fe with different deposi tion rates on hot silicon substrate. As-grown alloy films display semicondu ctor type optical absorption, but only Fe0.9Cr0.1Si2 film keeps the crystal line structure of beta -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. (C) 2001 Els evier Science B.V. All rights reserved.