INFLUENCE OF THE MICROSTRUCTURE ON THE THERMAL-PROPERTIES OF THIN POLYCRYSTALLINE DIAMOND FILMS

Highly oriented and columnar grained diamond layers only a few microns thick, deposited at different substrate temperatures (500, 550, and 8 00 degrees C) on silicon using microwave-plasma-assisted chemical vapo r deposition, are investigated by special photothermal techniques and high-resolution transmission electron microscopy (HRTEM). Small effect ive diamond-silicon boundary resistances of <4x10(-9) m(2)K/W are dete rmined for thermal conduction normal to the interface. Thermal conduct ivities normal to the interface, k(p)erpendicular to, are found to be about an order of magnitude greater than the conductivities parallel t o the interface, k(parallel to) (k(perpendicular to)/k(parallel to)=9- 18). The boundary resistances measured are in good agreement with limi ts estimated from the interface structure observed by HRTEM, which ind icate a low near-interfacial disorder for the layers. (C) 1997 America n Institute of Physics.