Electrically induced thermal transient experiments for thermal diffusity measurements on chemical vapor deposited diamond films
Elektrisch induzierte thermische Wellenmethode für thermische Diffusitätsmessungen an Diamantschichten
To investigate the in plane thermal diffusivity of chemical vapor deposited diamond layers, two new techniques were developed based on electrically induced converging and linear thermal waves. With these methods, free-standing, laser-cut diamond samples, 1 00 mu m or larger in thickness can be analyzed. Laser cutting leaves a graphitic surface layer along the cutting edge. Therefore, a short high voltage pulse, applied at the graphitic rim resistor, is used to generate a thermal transient. The propagation of the wave is measured optically either in the center of the circular disk or at one side of a bar shaped sample. Both techniques require only very little sample preparation. They are shown to be simple, accurate, and independent of sample thickness and induced energy. In order to analyze the experimental data we present both an analytical model and a numerical simulation.