Local atomic configurations, energy structure, and optical properties of implantation defects in Gd-doped silica glass: An XPS, PL, and DFT study

Abstract

The KUVI-SiO2 hosts were Gd-implanted and passivated using Bonilla's stable passivation conditions. Their electronic structure was studied employing X-ray Photoelectron (XPS) and Photoluminescence (PL) spectroscopies with the onward theoretical DFT-modeling of experimentally derived scenarios for pulsed Gd-implantation into amorphous matrix. Both experiment and theory report the unfavorability of substitutional Gd-defects formation. The most probable scenario of Gd accumulation in the host-structure is Gd-interstitials with the fabrication of ≡Si–O–[Gd]3+… clusters with partial location of Gd atoms in the vicinity of Si ODC's. Tempering reduces the Nomura's bonds-switching charge-transfer mechanism in the electronic structure of KUVI-SiO2:Gd and, with a high probability, leads to fabrication of Si QDs, which have been well recognized by the PL-technique. DFT calculations confidently demonstrate relatively low energy costs required for oxygen passivation by embedded Gd and the fabrication of Si-Si bonds inside the host.