Direct observation of the distribution of impurity in phosphorous/boron co-doped Si nanocrystals

Abstract

Doping in Si nanocrystals is an interesting topic and directly studying the distribution of dopants in phosphorous/boron co-doping is an important issue facing the scientific community. In this study, atom probe tomography is performed to study the structures and distribution of impurity in phosphorous/boron co-doped Si nanocrystals/SiO2 multilayers. Compared with phosphorous singly doped Si nanocrystals, it is interesting to find that the concentration of phosphorous in co-doped samples can be significantly improved. Theoretical simulation suggests that phosphorous–boron pairs are formed in co-doped Si nanocrystals with the lowest formation energy, which also reduces the formation energy of phosphorous in Si nanocrystals. The results indicate that co-doping can promote the entry of phosphorous impurities into the near-surface and inner sites of Si nanocrystals, which provides an interesting way to regulate the electronic and optical properties of Si nanocrystals such as the observed enhancement of conductivity and sub-band light emission.