Detection of hBN-cBN Transition

To the knowledge of the authors there are few experimental experiences concerning the discrimination of nucleation and growth of cBN. Schutze et al. [57] developed a simple method to control the cBN nucleation in situ by monitoring the substrate current. This is possible, for example, if in the RF sputter device the substrate electrode is operated with d.c. voltage. Fig. 8a shows the principle. 

Keeping all process parameters constant, an increase in the substrate current was observed if the deposition had been performed in the cBN mode, but it was not observed if the deposition was performed in an hBN mode. This can be explained as follows. The measured substrate current /sub = + -fsE = i(l + 7i) is th sum 

5 Vapor Phase Deposition of Cubic Boron Nitride Films 

There are still other methods which are suitable for controlling the phase evaluation in cBN films. Barth et al. [66] measured in situ infrared reflectance spectra during the deposition time and revealed different deposition processes on silicon and steel substrates, respectively. McKenzie et al. [48] concluded from in situ stress measurements that there is a stress threshold above which the cBN growth is beginning. However, in both cases the process conditions were not modified during film growth. 

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