Formation of gold nanoclusters in MgO by ion implantation at elevated temperatures

Gold nanoclusters were formed in (100) MgO containing nanosize cavities. Na nocavities were created by a combination of 30 keV He-3 implantation and su bsequent annealing. Au was introduced inside the cavities by 30 keV Au ion implantation. The implantation dose varied from 10(16) to 3 x 10(16) cm(-2) and the implantation temperature varied From room temperature (RT) to 1270 K. In the case of the RT implantations the samples were subsequently annea led stepwise in air up to 1370 K. The evolution of the implantation defects and the formation of nanoclusters was monitored by positron beam analysis (PBA), optical absorption spectrometry and Rutherford backscattering spectr oscopy (RBS)/channeling. Optical absorption resonance peaks were observed a t 570-610 nm for the RT implantations and at 525-550 nm for the implantatio ns carried out at elevated temperatures. In the case of 1270 K implantation an extra absorption peak at 818 nm was observed. The influence of the impl antation temperature on shape and position of the absorption band ascribed to nanoclusters is discussed. (C) 2000 Elsevier Science B.V. All rights res erved.