Grazing incidence X-ray study of Ge-nanoparticle formation in (Ge:SiO2)/SiO2 multilayers

Abstract We present the study of formation of Ge-nanoparticles (Ge-NP) in germanosilicate (Ge:SiO 2 ) multilayer (ML) films under thermal treatment. In anticipation of controllable formation of Ge-NP, ML films were prepared by magnetron deposition at room temperature as 20 bi-layer stacks, each bi-layer comprised of a 7 nm thick layer of (Ge + SiO 2 ) (molar ratio: 60:40) succeeded by a 7 nm thick layer of pure SiO 2 , and then annealed for 1 h, up to T a  = 900 °C. Formation and morphology of Ge-NP were analyzed by combining the information obtained from the grazing incidence small angle X-ray scattering and X-ray diffraction. It was found that precipitation of Ge-NP starts at T a  = 600 °C, while high degree of in-plane confinement and lateral ordering of rather uniform precipitated particles is achieved at T a  =  700–800 °C range. At still higher annealing temperature T a  > 800 °C, volume fraction of precipitated Ge-NP in SiO 2 matrix diminishes due to the out-diffusion of Ge atoms from the film, while Ge-NP are no more well confined to (Ge + SiO 2 ) layers.