ELECTRICAL-PROPERTIES OF POLYCRYSTALLINE BETA-SIC THIN-FILMS FOR HIGH-TEMPERATURE SENSORS GROWN BY THE ACTIVATED REACTIVE EVAPORATION PROCESS

Polycrystalline beta-SiC is expected to be an excellent semiconductor material for thin film temperature sensors which can measure the surfa ce temperature of ceramic turbine blades up to 1500-degrees-C. Films w ere deposited on thermally oxidized Si(100) substrates by the activate d reactive evaporation (ARE) process. The electrical properties, such as resistivity, carrier type, density and mobility, are some of the im portant factors determining sensor performance. Room temperature Hall measurements on the as-deposited silicon carbide films were carried ou t to investigate these properties. The effects of important deposition parameters, such as C2H2 pressure, substrate temperature and ARE elec trode power (plasma density) for the generation of glow discharge of a cetylene gas, on those properties are studied. It is found that the el ectrical properties of the films are very much dependent on those depo sition parameters. Under the optimum deposition conditions (C2H2 press ure 3 mTorr, substrate temperature 700-degrees-C and ARE electrode pow er 12.0-16.2 W), beta-SiC films with C/Si ratio 1.27-1.34 are obtained . The films show n-type conduction, resistivity 4.4-5.7 OMEGA cm, carr ier density (5.2-7.1) x 10(16) cm-3, and Hall mobility 17.4-19.8 cm2 V -1 s-1