Isovalent doping and the CiOi defect in germanium

Abstract

Oxygen-carbon defects have been studied for decades in silicon but are less well established in germanium. In the present study we employ density functional theory calculations to study the structure of the C i O i defect in germanium. Additionally, we investigate the interaction the C i O i defect with isovalent dopants such as silicon and tin. It is calculated that the C i O i defects will preferentially form near isovalent dopants in germanium. Interestingly the structure of the dopant-C i O i defects is different with the Sn residing next to the O i whereas the Si atom bonds with the C i . The differences in the structure of C i O i defects in the vicinity of isovalent dopants are discussed.

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.…”