Light-emitting defects formed in GeO/SiO₂ heterostructures with assistance of swift heavy ions

Germanium suboxide films and GeO/SiO₂ multilayer heterostructures deposited onto Si(001) substrates using evaporation in high vacuum were modified using irradiation of 167 MeV Xe⁺²⁶ ions with fluences varying from 10¹¹ to 10¹³ cm⁻². According to Raman spectroscopy data, the swift heavy ion irradiation does not lead to the expected decomposition of germanium suboxide in germanium nanoclusters and GeO₂. Infrared absorption spectroscopy measurements show that under irradiation the GeO/SiO₂ layers were intermixed with formation of Ge-O-Si bonds. We report strong photoluminescence in the visible range at room temperature, which is most probably due to Ge-related defect-induced radiative transitions. Moreover, a new infrared luminescence band (~0.8 eV) was observed in irradiated structures, which can be related to defects or defects complexes in Ge_xSi_yO₂ glass.