DESEGREGATION OF BORON AT THE GRAIN-BOUNDARIES OF THE IN-SITU BORON-DOPED DIAMOND FILMS

High quality in situ boron doped polycrystalline diamond films were gr own on the scratched Si (100) substrate. A saturated deionized water s olution of boron acid was chosen as a dopant source. The concentration profiles of boron, tantalum, and oxygen were examined by using scanni ng Auger nanoprobe and secondary ion mass spectroscopy. The boron atom s are uniformly distributed inside each diamond grain. However, no Aug er signal from boron was observed at grain boundaries within the detec tion limit. Tn contrast, tantalum atoms are uniformly distributed acro ss diamond grains and grain boundaries. A simple model was proposed in explaining the boron desegregation. (C) 1995 American Institute of Ph ysics.