Influence of the multilayer system on the structure and photoluminescence of GeOx thin films

Amorphous GeOx/SiO2 multilayers (12 and SiO2 powders onto the Si substrates maintained at 100°C. Structural study by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared-absorption (FTIR) spectrometry, and transmission electron microscopy (TEM) was carried out. These techniques allowed us to follow the structural evolution, and phase decomposition due to annealing in the GeOx thin films and the multilayers annealed up to 900°C, and appearance of amorphous and crystallized germanium aggregates. For Ta≥ 400°C, the photoluminescence band around 1eV attributed to confinement effect in amorphous germanium aggregates was observed. Comparison of the luminescence in multilayer and GeOx thin film showed that in multilayer, although the control of the nanocrystals size isnt complete, the SiO2 barriers tend to enhance the intensity and reduce FWHM of the luminescence bands. This means that the confinement effect in the germanium aggregates in GeOx matrix is enhanced in multilayer system.