The effect of external field on the electronic properties of silicon nanodots

It is reported that silicon nanodots (SiNDs) present excellent optical and electronic properties. For applications of SiNDs in the electric industry, external fields (such as the strain field ɛ and electric field F) are an important factors modulating the properties of SiNDs. The size dependences of the band gap for SiNDs under ɛ and F were investigated by using first principle calculations based on density functional theory. The mechanism of the band gap variation is different for SiNDs with tetrahedron-centered and hexagon-centered structures. Especially, when a multi-field is applied, namely ɛ and F co-exist, there is an interaction effect between ɛ and F. The strain field can weaken or enhance the effect of the electric field. In addition, the interaction is structure-dependent. The combination of ɛ and F provides additional flexibility to modulate the properties of SiNDs. These external fields can be used for designing new classes of optical and electronic nanodevices and external field sensors.