An oxygen free 6061 aluminum alloy surface produced by ammonia dc plasma and sputtering processes

An oxygen free polycrystalline 6061 aluminum alloy surface was obtained for the first time in an UHV environment (1×10−9 to 3×10−9 Torr) after dc ammonia plasma treatment in a separate vacuum system. The specimen was first sputtered and processed in the plasma chamber for about 1 h, transferred after air exposure into the UHV chamber, then cleaned by 2.8 keV Ar+ ion bombardment for about 10 min to remove the air-grown oxide. An oxygen free 6061 aluminum surface was observed using Auger electron spectroscopy. Regrowth of the oxide layer in the UHV environment was monitored versus time. A possible cleaning mechanism by the ammonia plasma is proposed. This oxygen free surface is key to achieving thin film growth/deposition on aluminum or its alloys.