Oxygen behaviour during PIII-nitriding of aluminium

During nitrogen plasma immersion ion implantation (PIII) treatment of pure aluminium at elevated temperatures between 250 degreesC and 500 degreesC, a rather high oxygen concentration of up to 20 at.% is observed in the treat ed samples, despite a base pressure of 10(-5) Pa and a working pressure of 0.2 Pa. This behaviour is caused by oxygen uptake via surface defects creat ed by the ion bombardment, as shown in a control experiment with Ar implant ation. A thermally activated oxygen diffusion tail is observed for nitrogen implantation, which can be explained by the diffusion of Al cations in AIN . (C) 2001 Elsevier Science B.V. Ail rights reserved.