NANOMETER-SIZED GE PARTICLES IN GEO2-SIO2 GLASSES PRODUCED BY PROTON IMPLANTATION - COMBINED EFFECTS OF ELECTRONIC EXCITATION AND CHEMICAL-REACTION

It was reported [H. Hosono et al., Appl. Phys. Lett. 65, 1632 (1994)] that nanometer-sized crystalline (nc) Ge colloid particles were formed by implantation of protons into 0.1 GeO2-0.9 SiO2 glasses at room tem perature. The depth profiles of Ge colloids and the density of Si-OH o r Ge-OH created by the implantation were measured and compared with th ose of energy deposition in order to examine the formation mechanism o f Ge colloids by proton implantation. The depth region of nc-Ge partic les was found to correspond to the overlapped region between the OH di stribution and the peak of electronic energy deposition. Transmission electron microscopic observation revealed that the size of Ge colloid particles created by proton implantation was close to that of GeO2-ric h particles occurring in the substrate glasses. These results indicate that GeO2-rich particles are converted into Ge particles by a combine d effect of the electronic excitation and the chemical reaction of imp lanted protons. A mechanism was proposed consisting of displacement of bridging oxygen into interstitials by electronic excitation and subse quent trapping of the oxygen interstitials by a formation of OH groups . (C) 1997 American Institute of Physics. [S0021-8979(97)06619-X].