First principles calculations of ZnS:Te energy levels

Abstract

A comprehensive density-functional calculation for the ZnS:Te isoelectronic impurity state is presented. We deploy a charge patching method that enables us to calculate systems containing thousands of atoms. We found that the impurity state is only weakly localized, and previous calculations using 64-atom cells were severely unconverged. Our calculated impurity binding energy agrees with experimental photoluminescence excitation spectrum. We have analyzed the impurity wave function in both real space and the reciprocal space, and in terms of the host bulk valence bands. We have also calculated the Stokes shifts and Jahn-Teller effects. We found small Stokes shift compared to the experimental results, which might indicate the limitations of the current method. We also calculated the Te n clusters and their impurity states. We found six ͑counting spin͒ bound states inside the band gap of ZnS for all 1рnр4. We obtained pressure coefficients for Te n , all close to the value of bulk ZnS. This is consistent with the fact that the impurity states of Te n consist almost entirely of the bulk valence bands of ZnS. Finally, we have calculated the effects of spin-orbit coupling for the impurity state eigenenergies.

Arsenic in ZnO and GaN: Substitutional Cation or Anion Sites?

“…It is quite obvious that As atoms on Ga sites do not contribute to the stability of the compound, since no chemical bonds will be formed with the neighboring N or As atoms. Our findings clearly confirm the theoretical predictions of Van De Walle and Neugebauer [29] who have pointed out As Ga anti-site formation as a problem with respect to the growth of GaAsN compounds, while a large number of theoretical studies have completely neglected this possibility [44][45][46][47][48][49][50][51][52][53][54][55]. While the preservation of chemical bonds probably holds in the case of GaAs lightly doped with N, trying to explain the properties of GaNrich alloys doped with As based on the assumption that all chemical bonds between Ga and N or Ga and As are preserved will definitely yield a too simplified picture.…”

Jamming transition in emulsions and granular materials

“…11b-2 and Fig. 11b-3 has been reported by various authors studying dense liquids and granular materials [41,43,44,45]. The authors of Ref.…”

Electronic Structure of Disordered Conjugated Polymers: Polythiophenes

“…The approach we take to tackle the problem of the electronic structure of conjugated polymers is centered around our recently developed charge patching method [12][13][14][15] for electronic structure of organic systems 16 which enables studies of systems with more than ten thousand atoms with the accuracy similar to the one of DFT in local density approximation (LDA). Atomic structure is found from a classical molecular dynamics (MD) simulation.…”