Effects of composition and compositional distribution on the electronic structure of ZnSe 1− x Te x ternary quantum dots

We report results of first-principles density functional theory (DFT) calculations for the electronic structure of ZnSe 1− x Te x ternary quantum dots (TQDs) and the effects of composition and compositional distribution on the electron density distribution, electronic density of states, and band gap. We analyze the electronic structure of five types of nanocrystal configurations, namely, pristine ZnSe and ZnTe quantum dots, as well as ZnSe/ZnTe core/shell, ZnTe/ZnSe reverse core/shell, and randomly alloyed ZnSe 1− x Te x TQDs. We find that the band gaps for ZnSe/ZnTe core/shell TQDs are nonlinearly dependent on the number of Te atoms in the shell, whereas presence of Te in the core of alloyed ZnSe 1− x Te x TQDs modifies the electronic energy levels abruptly and significantly in the limits of x → 0 and x → 1. Our results imply that distribution of Te atoms in the TQD in the form of a ZnSe/ZnTe core/shell configuration allows for optimum tunability of the band gap and wave function confinement in TQDs.