Nucleation and growth of diamond films on single crystal and polycrystalline tungsten substrates

Silicon has been the most widely studied substrate for the nucleation and g rowth of CVD diamond films. However, other substrates are of interest, and in this paper, we present the results of a study of the biased nucleation a nd growth of diamond films on bulk single and polycrystalline tungsten. Dia mond films were nucleated and grown, using a range of bias and reactor cond itions, and characterized by Raman spectroscopy and scanning electron micro scopy (SEM). High-quality (100) textured films (Raman FWHM <4 cm(-1)) could be grown on both single and polycrystalline forms of the tungsten substrat e. On carefully prepared substrates, by varying the bias treatment, it was possible to determine the nucleation density over a 4-5 order range, up to similar to 10(9) cm(-2). Raman measurements indicated that the diamond film s grown on bulk tungsten exhibited considerable thermal stress (similar to 1.1 GPa), which, together with a thin carbide layer, resulted in film delam ination on cooling. The results of the study show that nucleation and growt h conditions can be used to control the grain size, nucleation density, mor phology and quality of CVD diamond films grown on tungsten. (C) 2000 Elsevi er Science S.A. All rights reserved.