FABRICATION OF DIAMOND THIN-FILM THERMISTORS FOR HIGH-TEMPERATURE APPLICATIONS

CVD diamond thin-film thermistors have been fabricated in various geometries and at different doping levels in an effort to achieve practical resistance-vs.-temperature characteristics. Typical activation energy values reported for polycrystalline films were combined with a targeted resistance range to plot an idealized relationship between resistance and temperature for CVD diamond thin films. The optimum device geometry and boron concentration were subsequently approximated from these ideal plots. Fabricated devices were electrically characterized in air at temperatures ranging from 25-degrees-C to over 500-degrees-C. Repeatability was demonstrated over two temperature cycles and stability was maintained at 500-degrees-C for 9 h. Effects of varying thermistor geometry and boron dopant concentration to achieve useful resistance temperature relationships will be discussed.