Resistivity and Structure of Cr–SiO Cermet Films

Abstract
The structure, resistivity, and temperature coefficient of resistance (TCR) of Cr-SiO films with controlled compositions from 0 to 50 at. % SiO have been investigated. Randomly disordered films condense at −196 °C. Higher temperatures introduce varying degrees of order accompanied by disproportionation of SiO and reaction with Cr. This leads to nonhomogeneous structures consisting of amorphous SiO2 and Cr–Si phases according to the binary diagram. Metallic particles of α-Cr and Cr3Si, with either little or no long-range order or at the most partially crystalline, provide conductivity which decreases with increasing SiO2 concentration. The resistance decreases during annealing are proportional to the Cr3Si concentration over a wide composition range. The TCR's of highly disordered films are negative and shift toward positive values upon annealing. Their interpretation requires metallic and thermally activated conduction mechanisms in parallel. The resistivity and TCR changes during annealing are attributed to recrystallization and bridging between islands.