Depth profiles of Argon incorporated into Boron Nitride films during preparation and their temperature dependent evolution

Abstract Cubic (c-) as well as hexagonal (h-) Boron Nitride (BN) films, prepared by different ion beam assisted deposition techniques on top of Si(0 0 1) substrates, were studied with respect to the depth profiles of incorporated Argon using Rutherford backscattering (RBS). Quantitative analysis of such RBS spectra clearly demonstrated a preferential trapping of Ar close to the substrate, where high resolution transmission electron microscopy revealed the presence of an amorphous intermixed and an h-BN layer on top of each other. Subsequent annealing steps at 730, 960 and 1100 °C combined with RBS allowed to determine the total amount of Ar diffusing out of a sample as well as the depth profiles of the residual Ar. For temperatures below 750 °C neither in c-BN nor in h-BN any Ar diffusion is observed. At 970 °C a clear outdiffusion of Ar is found in h-BN samples, while in c-BN a redistribution of the profiles occurs with a significant accumulation of Ar towards the surface. At 1100 °C, a loss of Ar becomes visible also for c-BN films and is attributed to grain boundary diffusion, while Ar trapped within c-BN grains appears still to be immobile.