Strategies to suppress A-center formation in silicon and germanium from a mass action analysis viewpoint

Abstract

We investigate the impact of tin doping on the formation and the thermal stability of the vacancy-oxygen (VO or A-center) in electron-irradiated Czochralski silicon and its conversion to the VO 2 defects. Previous experimental studies are consistent with the viewpoint that tin (and other oversized isovalent atoms) doping suppresses the formation of the A-center. The results are discussed in view of recent density functional theory calculations, whereas we employ mass action analysis to calculate the impact of isovalent dopants on the suppression of the A-center. We propose point defect engineering strategies to suppress the concentration of the deleterious Acenters in silicon and in related materials such as germanium.2

Diffusion and Dopant Activation in Germanium: Insights from Recent Experimental and Theoretical Results

“…Considering oxygen-related defects in Ge [108][109][110][111][112][113] (refer to Section 7 for what follows), the main benefit for introducing isovalent dopants is to anchor or attract the lattice vacancies, which would otherwise bind with the oxygen atoms [39,112]. In DFT calculations, it was calculated that the SnV defect is more bound compared to the VO defect by 0.2 eV [112], and thus, if there is enough Sn in the lattice (i.e., more than the existing oxygen) most vacancies will be trapped by the Sn atoms limiting the concentration of the VO pairs. This is analogous to the defect engineering strategies employed using isovalent dopants to minimize the formation of the deleterious oxygen-vacancy defects in Si [86].…”