TRAVELING-WAVE METHOD FOR MEASUREMENT OF THERMAL-CONDUCTIVITY OF THIN-FILMS

We present here the design of a novel and simple setup for measuring t he thermal conductivity of thin films. This method is based on the wel l known principle of phase lag of a traveling thermal wave. In the pre sent setup, the traveling thermal wave is generated in the thin film b y irradiating its one edge by an infrared laser. The phase lag (Delta theta) between the excitation wave and the resulting thermal wave, at a variable distance d from the edge of the sample, is determined by me asuring the deflection of another ''probe-laser.'' The thermal diffusi vity is then directly calculated from the slope of the plot between De lta theta and d. This method offers an accuracy of better than +/-5%. (C) 1997 American Institute of Physics. [S0034-6748(97)01811-X].