Electronic structure of the Cd vacancy in CdTe

Abstract

By means of a tight binding parametrization of the band structure of cadmium telluride, in conjunction with the Green's function method the density of states of the perfect crystal is determined. Various parametrizations for this compound are compared. Next, the energy levels for the Cd vacancy are calculated taking into account the change in the wave functions around the missing atom as well as the various possibilities for the charged state a t this site. Spin-orbit coupling is not taken into account, nor the possible neighbor relaxation around the vacancy.In Verbindung mit der Methode der Greenschen Funktionen wird mittels ,,tight-binding" Parametrisierung der Bandstruktur von Kadmiumtellurid die Zustandsdichte des perfekten Kristalls bestimmt. Verschiedene Parametrisierungen fur diese Verbindung werden verglichen. Unter Beriicksichtigung sowohl der Anderung der Wellenfunktion um das fehlende Atom als auch der verschiedenen Moglichkeiten fur den Ladungszustand an diesem Platz werden dann die Energieniveaus fur die Cd-Leerstelle berechnet. Weder Spin-Bahnkopplung noch eine mogliche Nachbarrelaxation um die Leerstelle werden beriicksichtigt.

Band Alignments, Band Gap, Core Levels, and Valence Band States in Cu3BiS3 for Photovoltaics

“…CdTe is an “archetypical II–VI” material with a VBM mostly comprising bonding cation-p/anion-p states and a CBM mostly comprising antibonding cation-s/anion-p states, with the corresponding antibonding (bonding) states occurring higher (lower) in the CB (VB) with respect to the band edge. , The cation-d orbitals of CdTe are bound too strongly to significantly interact with valence states and therefore do not influence the VBM. However, in the copper-containing compounds (CIGS, CZTS, CAS, and CBS), the full Cu d states are close in energy to the full anion-p orbitals.…”

Small hole polaron in CdTe: Cd-vacancy revisited

“…The hole polaron formation accompanying the in CdTe was never described before by means of ab-initio methods. Some speculations have been made 26 27 regarding a Jahn-Teller distortion of the in CdTe in analogy to the Zn vacancy in ZnSe. In fact, a general model for the localised hole plus trigonal distortion has been proposed for BeO, ZnO, ZnSe, ZnS, and CdS 26 .…”

XANES and Unoccupied DOS of Sulfides and Selenides of Zn and Cd

“…Fig. 4 visualizes the fact that the bottom of the conduction band for all compounds A II B VI is formed of s-states of the metal (in agreement with [16,18,19]). But we have obtained a greater distance (1.2 to 1.5 eV) between the main maxima of unoccupied s-and p-states of Cd in CdS than one received [16] for Cd in CdTe.…”

“…The densities of the unoccupied pstates of Te in CdTe [16] are presented to show that the calculations of some authors with other approximations (e.g. with the tight-binding method variant) give the same falling down to zero of the DOS at about 6 eV ( Fig.…”

“…The results of experimental (K-absorption edges) and theoretical investigations of cubic CdS and CdSe. The density of p-states of Te in CdTe are taken from [16]…”