DIRECT MEASUREMENT OF CVD DIAMOND FILM THERMAL-CONDUCTIVITY BY USING PHOTOACOUSTICS

Photoacoustics (PA) is a type of photothermal effect and differs from the other one, known as the ''mirage'' effect, by the generation of th ermal deflection waves as acoustic waves in a gas adjacent to the samp le due to the modulated light absorption. We analyzed the feasibility of using PA for direct measurement of thermal conductivity of diamond films. The method was tested on two types of diamond polycrystalline f ilms grown by chemical vapor deposition in plasma of direct current an d microwave discharges. The thermal conductivity properties of the dia mond films obtained are discussed by taking into account the Raman, ph otoluminescent, cathodoluminescent and other properties of these mater ials. The thermal conductivity values are shown to depend on polycryst alline diamond him structural characteristics that are defined by the conditions of the deposition. (C) 1998 Elsevier Science S.A. All right s reserved.