Dimensional changes of Al2O3, MgO, MgAl2O4, AlN and Si3N4 by helium implantation

Ribbons of aluminum-oxide, magnesium-oxide, magnesium-aluminum-spinel, alum inum-nitride and silicon-nitride were implanted with helium to about 1/3 of their thickness to concentrations from 0.3 to 300 at, ppm. Dimensional cha nges after implantation and during subsequent annealing up to temperatures of 1600 degrees C were determined from the bending of the specimens by surf ace profilometry. The high sensitivity of this method allowed measurements to very low doses, giving well resolved recovery steps in contrast to previ ous literature results. A comparison to irradiations without implantation s howed that volume expansion is mainly due to displacement defects. At heliu m concentrations above about 30 at. ppm, volume increase was observed at hi gher temperatures which is ascribed to the onset of bubble swelling by vaca ncy accumulation at helium clusters. (C) 2000 Elsevier Science B.V. All rig hts reserved.