Optical and structural properties of Ge-ion-implanted fused silica after annealing in different ambient conditions

Abstract

Ge+ ions are implanted into fused silica glass at room temperature and a fluence of 1 × 1017 cm−2. The as-implanted samples are annealed in O2, N2 and Ar atmospheres separately. Ge0, GeO and GeO2 coexist in the as-implanted and annealed samples. Annealing in different atmospheres at 600 °C leads each composite to change its content. After annealing at 1000 °C, there remains some amount of Ge0 in the substrates. However, the content of Ge decreases due to out-diffusion. After annealing in N2, Si–N composite is formed. The absorption peak of GeO appears at 240 nm after annealing in O2 atmosphere, and a new absorption peak occurs at 418 nm after annealing in N2 atmosphere, which is attributed to the Si–N composite. There is no absorption peak appearing after annealing in Ar atmosphere. Transmission electron microscopic images confirm the formation of Ge nanoparticles in the as-implanted sample and GeO2 nanoparticles in the annealed sample. In the present study, the GeO content and the GeO2 content depend on annealing temperature and atmosphere. Three photoluminescence emission band peaks at 290, 385 and 415 nm appear after ion implantation and they become strong with the increase of annealing temperature below 700 °C, and their photoluminescences recover to the values of as-grown samples after annealing at 700 °C. Optical absorption and photoluminescence depend on the annealing temperature and atmosphere.