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

摘要

Cubic (c-) as well as hexagonal (h-) Boron Nitride (BN) films, prepared by different ion beam assisted deposition techniques on top of Si(001) 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 deg 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 deg C neither in c-BN nor in h-BN any Ar diffusion is observed. At 970 deg 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 deg C, a lsos of Ar becomes visible also for c-BN films and is attributed to grain bounary diffusion, while Ar trapped within c-BN grains appears still to be immobile.