Density functional theory study on the boron and phosphorus doping of germanium quantum dots

Abstract

Doping is a crucial way of tuning the properties of semiconductor quantum dots (QDs). As one type of important semiconductor QDs, germanium (Ge) QDs have been recently doped with boron (B) and phosphorus (P) through a gas-phase synthesis approach successfully. However, theoretical understanding about the structural and electronic properties of doped Ge QDs remains rather limited. Here we investigate the doping of Ge QDs with B and P in the framework of density functional theory. The formation energies and electronic structures of singularly B- or P-doped Ge QDs and B/P-codoped Ge QDs are systematically studied. It is found that both B and P prefer the near-surface region of Ge QDs. The electronic structures of Ge QDs can be effectively tuned by B and P doping. The B/P codoping may facilitate the incorporation of B and P into Ge QDs, resulting in the further modification of the electronic structures of Ge QDs.