Electrical properties of polycrystalline β-SiC thin films for high temperature sensors grown by the activated reactive evaporation process

Abstract

Polycrystalline β-SiC is expected to be an excellent semiconductor material for thin film temperature sensors which can measure the surface temperature of ceramic turbine blades up to 1500°C. Films were deposited on thermally oxidized Si(100) substrates by the activated reactive evaporation (ARE) process. The electrical properties, such as resistivity, carrier type, density and mobility, are some of the important factors determining sensor performance. Room temperature Hall measurements on the as-deposited silicon carbide films were carried out to investigate these properties. The effects of important deposition parameters, such as C 2 H 2 pressure, substrate temperature and ARE electrode power (plasma density) for the generation of glow discharge of acetylene gas, on those properties are studied. It is found that the electrical properties of the films are very much dependent on those deposition parameters. Under the optimum deposition conditions (C 2 H 2 pressure 3 m Torr, substrate temperature 700°C and ARE electrode power 12.0–16.2 W), β-SiC films with C/Si ratio 1.27–1.34 are obtained. The films show n-type conduction, resistivity 4.4–5.7 ωcm, carrier density (5.2–7.1) × 10 16 cm -3 , and Hall mobility 17.4–19.8 cm 2 V -1 s -1 .