Influence of silicon dangling bonds on germanium thermal diffusion within SiO2 glass

We study the influence of silicon dangling bonds on germanium thermal diffusion within silicon oxide and fused silica substrates heated to high temperatures. By using scanning electron microscopy and Rutherford backscattering spectroscopy, we determine that the lower mobility of Ge found within SiO2/Si films can be associated with the presence of unsaturated SiOx chemical bonds. Comparative measurements obtained by x-ray photoelectron spectroscopy show that 10% of silicon dangling bonds can reduce Ge desorption by 80%. Thus, the decrease of the silicon oxidation state yields a greater thermal stability of Ge inside SiO2 glass, which could enable to considerably extend the performance of Ge-based devices above 1300 K.