The CiCs(SiI)n defect in silicon from a density functional theory perspective

Carbon is an important defect in silicon (Si) as it can interact with intrinsic point defects and affect the operation of devices. In heavily irradiated Si containing carbon the initially produced carbon interstitial - carbon substitutional (CiCs) defect can associate with self-interstitials (SiI’s) to form, in the course of irradiation, the CiCs(SiI) defect and further to form larger complexes namely CiCs(SiI)n defects by the sequential trapping of self-interstitials defects. In the present study, we use density functional theory to clarify the structure and energetics of the CiCs(SiI)n defects. Here we report that the lowest energy CiCs(SiI) and CiCs(SiI)2 defects are strongly bound with -2.77 eV and -5.30 eV, respectively

Effect of tin doping on oxygen- and carbon-related defects in Czochralski silicon

Experimental and theoretical techniques are used to investigate the impact of tin doping on the formation and the thermal stability of oxygen- and carbon-related defects in electron-irradiated Czochralski silicon. The results verify previous reports that Sn doping reduces the formation of the VO defect and suppresses its conversion to the VO2 defect. Within experimental accuracy, a small delay in the growth of the VO2 defect is observed. Regarding carbon-related defects, it is determined that Sn doping leads to a reduction in the formation of the CiOi, CiCs, and CiOi(SiI) defects although an increase in their thermal stability is observed. The impact of strain induced in the lattice by the larger tin substitutional atoms, as well as their association with intrinsic defects and carbon impurities, can be considered as an explanation to account for the above observations. The density functional theory calculations are used to study the interaction of tin with lattice vacancies and oxygen- and carbon-related clusters. Both experimental and theoretical results demonstrate that tin co-doping is an efficient defect engineering strategy to suppress detrimental effects because of the presence of oxygen- and carbon-related defect clusters in devices

Point defect engineering strategies to suppress A-center formation in silicon

We investigate the impact of tin doping on the formation of vacancy-oxygen pairs ( VO or A-centers) and their conversion to VO(2) clusters in electron-irradiated silicon. The experimental results are consistent with previous reports that Sn doping suppresses the formation of the A-center. We introduce a model to account for the observed differences under both Sn-poor and Sn-rich doping conditions. Using density functional theory calculations, we propose point defect engineering strategies to reduce the concentration of the deleterious A-centers in silicon. We predict that doping with lead, zirconium, or hafnium will lead to the suppression of the A-centers