title: Stability of the DX- center in GaAs quantum dots.
abstract: Using a first-principles band structure method, we study how the size of quantum dots affects the stability and transition energy levels of defects in GaAs. We show that, although a negatively charged DX- center is unstable in bulk GaAs:Si with respect to the tetrahedral coordinated Si(-)(Ga), it becomes stable when the dot size is small enough. The critical size of the dot is about 14.5 nm in diameter. The reason for the stabilization is the strong quantum-confinement effect, which increases the formation energy of Si(-)(Ga) more than that of the DX- defect center. Our studies show that defect properties in quantum dots could be significantly different from those in bulk semiconductors.
authors.affiliation: National Renewable Energy Laboratory, Golden, CO 80401, USA. jingbo_li@nrel.gov
authors.forename: Jingbo
authors.initials: J
authors.lastname: Li
authors.forename: Su-Huai
authors.initials: SH
authors.lastname: Wei
authors.forename: Lin-Wang
authors.initials: LW
authors.lastname: Wang