IMPORTANCE OF IMPLANTATION SEQUENCE IN THE FORMATION OF NANOMETER-SIZE COLLOID PARTICLES EMBEDDED IN AMORPHOUS SIO2 - FORMATION OF COMPOSITE COLLOIDS WITH CU CORE AND A CU2O SHELL BY COIMPLANTATION OF CU AND F

A striking difference in the properties of nanosized colloid particles between amorphous SiO2 substrates implanted with Cu and F ions in a differing sequence is reported. No significant change in an optical band peaking at 2.2 eV due to plasma oscillation of Cu nanosize colloids is observed by implanting F and then Cu. The 2.2 eV band is not perceived with implantation of F ions into Cu-implanted substrates. Although colloid particles identified are Cu in the former sequence, those formed in the latter have a dual structure composed of Cu (core) and Cu2O (shell). This is explained by oxidation of the outer part of Cu colloids by energetic O recoiled from the silica structure by implanted F. © 1994 The American Physical Society.