Dynamic hyperfine interactions in 111In(111Cd)-doped ZnO semiconductor: PAC results supported by ab initio calculations

• Published in: Physica. B, Condensed matter Condensed matter, 2012-08, Vol.407 (16), p.3121-3124
• Main Authors: Muñoz, Emiliano L., Mercurio, Marcio E., Cordeiro, Moacir R., Pereira, Luciano F.D., Carbonari, Artur W., Rentería, Mario
• Format: Article
• Language: English
• Subjects: Cadmium; Cd impurities; Charge; Condensed matter; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Defects and impurities in crystals; microstructure; Doping and impurity implantation in iii-v and ii-vi semiconductors; Dynamic tests; Dynamics; Electric-field gradient; Electron states; Exact sciences and technology; FP-APW+lo; Mathematical models; Methods of electronic structure calculations; Perturbed-angular correlations; Physics; Semiconductors; Structure of solids and liquids; crystallography; Zinc oxide; ZnO
• ISSN: 0921-4526; 1873-2135
• DOI: 10.1016/j.physb.2011.12.041

In this work, we present results of Time-Differential γ–γ Perturbed-Angular-Correlations (PAC) experiments performed in 111Cd-doped ZnO semiconductor. The PAC technique has been applied in order to characterize the electric-field-gradient (EFG) tensor at (111In (EC)→) 111Cd nuclei located, as was later demonstrated, at defect-free cation sites of the ZnO host structure. The PAC experiments were performed in the temperature range of 77–1075K. At first glance, the unexpected presence of low-intensity dynamic hyperfine interactions was observed, which were analyzed with a perturbation factor based on the Bäverstam and Othaz model. The experimental EFG results were compared with ab initio calculations performed with the Full-Potential Augmented Plane Wave plus local orbital (FP-APW+lo) method, in the framework of the Density Functional Theory (DFT), using the Wien2K code. The presence of the dynamic hyperfine interactions has been analyzed enlightened by the FP-APW+lo calculations of the EFG performed as a function of the charge state of the cell. We could correlate the large strength of the dynamic hyperfine interaction with the strong variation of the EFG due to changes in the electronic charge distribution in the Cd vicinity during the time-window of the PAC measurement. It was also revealed that the Cd impurity decays to a final stable neutral charge state (Cd2+) fast enough (in few ns) to produce the nearly undamped observed PAC spectra.