The electrical resistance of the group IV transition metal monocarbides and mononitrides in the temperature range 20–1000°C

Abstract

The temperature dependence of the electrical resistance and the resistance stability of the group IV transition metal carbides and nitrides has been studied in order to examine their potential for elevated temperature resistance strain gauge application. The electrical resistance of these materials was studied in the temperature range 20–1000°C under vacuum via the four-probe method. The specimens for the measurements were prepared as thin films by several evaporation and sputtering techniques. The electrical properties of these transition metal compounds were found to be strongly composition dependent. An effort was made to explain the difference in the electrical conduction, metallic conductor or semiconductor, reported in this group of materials. The resistivity of the samples increased and their temperature coefficient of resistance (TCR) values decreased from positive to negative as the vacancy concentration increased. The presence of both a low TCR and a high resistance stability seemed to be mutually exclusive in this group of materials. However, the carbides had a lower TCR and a higher resistance stability than their corresponding nitrides. A high-temperature resistance saturation effect was observed in some of the materials and resulted in a low TCR. For a thin film transition metal compound with resistivity in the range of 900–1000 μΩ cm, a very low temperature-dependent resistance may be expected which makes it a good candidate for elevated temperature resistance strain gauge applications.