Abstract
Using ab initio calculations, we investigate the interactions among neutral excess oxygen atoms and amorphous silica (a-SiO2), along with hole trapping on neutral excess-oxygen defects. The calculations demonstrate that the interaction of excess oxygen with the a-SiO2 network results in two distinct defect structures referred to as the oxygen bridge-bonded (OBB) and peroxy linkage configurations. The OBB configuration may relax to a lower-energy structure after trapping a hole, representing a potential relaxation channel to the peroxy radical (POR) defect. The calculated hyperfine parameters are in excellent agreement with POR defect experiments and show that the oxygen atoms trapping the unpaired spin are bound to only one silicon atom. This implies that the OBB configuration is the major precursor of POR defects.
Highlights
Oxygen gas is traditionally used in silicon oxidation
The peroxy linkage (POL) and oxygen bridge-bonded (OBB) configurations were introduced by optimizing the model with an extra atomic oxygen inserted in a randomly selected void in the defectfree model
The results suggest that the POL configurations are energetically preferred to the OBB configurations
Summary
Using real-space multigrid electronic structure calculations, Jin et al.[7] found that the energy of the OBB configuration was 0.94 eV higher than that of the POL configuration in an α-quartz supercell with 72 host atoms They proposed a new diffusion mechanism for neutral atomic oxygen in a-SiO2; this mechanism involved the interconversion between the POL and OBB configurations in the neutral charge state, leading to the diffusion of neutral atomic oxygen in a-SiO2. Despite the numerous pioneering works, the POL and OBB configurations in a-SiO2 remain poorly understood in terms of their structural parameters and electronic properties Their charge states are unknown, leaving considerable space for speculation. A possible mechanism for the generation of PORs is discussed, including a comprehensive explanation of the effect of the a-SiO2 network
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