Hydrogen incorporation during nucleation and growth of c-BN films

The hydrogen content of BN films deposited by the ICP plasma method from trimethyl borazine and N-2 has been investigated integrally and spatially resolved by elastic recoil detection. Hydrogen contents between 15% and 25% have been found for conditions allowing the formation of c-BN compared with 4%-10% for h-BN conditions (low bias voltages). However, under c-BN conditions hydrogen is concentrated within the sp(2) parts of the film, particularly within the nucleation layer. Addition of hydrogen to the gas phase prevents the formation of c-BN and leads to h-BN films with high hydrogen contents. FTIR examination shows that the films do not contain BH and NH bonds; traces of OH and CHx do not add up to the total hydrogen content. Therefore most of the hydrogen must be free, for example incorporated on interstitials.