Formation of germanium nanocrystals and amorphous nanoclusters in GeO[SiO] and GeO[SiO$_2$] films using electron beam annealing

Electron beam annealing was carried out to form amorphous and crystalline germanium clusters in GeO[SiO] and GeO[SiO$_2$] films deposited on quartz and monocrystalline silicon substrates. Using electron microscopy, Raman spectroscopy, and light transmission and reflection spectroscopy, the structural transformations of the films and their optical properties were studied. From the analysis of Raman spectra, it was shown that amorphous germanium nanoclusters are present in the as-deposited GeO[SiO] film, while they are not observed in the as- deposited GeO[SiO$_2$] film. Regimes of electron beam annealing which are necessary for the formation of germanium nanocrystals in GeO[SiO] and GeO[SiO$_2$] films were found. It was shown that, at the same annealing parameters, the fraction of the crystalline phase of germanium in GeO[SiO] films were smaller than in GeO[SiO$_2$] films. In addition, it was found that the fraction of the crystalline phase at the same annealing parameters is larger for films on a quartz substrate than on monocrystalline silicon substrate. The sizes of germanium nanocrystals formed as a result of electron beam annealing were determined from Raman spectra analysis. The proposed method of obtaining amorphous germanium nanoclusters and nanocrystals in films of nonstoichiometric germanosilicate glasses using electron beam annealing can be used to create ordered arrays of such nanostructures.