Proton-implantation-induced nanosized Ge crystal formation in SiO2:GeO2 glasses

Nanometer-sized crystalline Ge colloid particles in 9SiO(2)-1GeO(2) glasses were formed by implantation of protons at 1.5 MeV without post-thermal annealing. Although oxygen-deficient type point defects associated with Ge ions were primarily formed to fluences less than or similar to 1X10(17) cm(-2), the formation of Ge fine crystalline particles was observed for fluences greater than or similar to 5X10(17) cm(-2). No formation of Ge colloids and the Ge-related point defects were noted for implantation of 1.5 MeV He+ to a fluence of 1X10(18) cm(-2). The depth of Ge colloid formation layers was 22-26 mu m from the implanted surface. This depth region agreed well with the peak region of electronic energy deposition. Ge-OH groups were formed preferentially over Si-OH groups upon implantation of protons and the decay curve upon isochronal annealing was close to that of the optical absorption at similar to 3 eV, which was attributed to nanometer-sized Ge. A red photoluminescence peaking at similar to 1.9 eV was observed for all the implanted substrates. A tentative formation mechanism of Ge colloids in these glasses was proposed. (C) 1996 American Institute of Physics.