Eur. Phys. J. B 84, 183-195 (2011)
https://doi.org/10.1140/epjb/e2011-20575-1

Regular Article

Ion distribution preferences in ternary crystals Zn_xCd_1−xTe, Zn_1−xHg_xTe and Cd_1−xHg_xTe

¹ INFN-Laboratori Nazionali di Frascati, Via E. Fermi 40, 00044 Frascati, Italy
² P.N. Lebedev Physical Institute, Russian Academy of Science, Leninsky prosp. 53, Moscow 119991, GSP-1, Russia
³ Instytut Fizyki, Universytet Jagiellonski, Reymonta 4, 30-059 Krakow, Poland
⁴ European Commission, Joint Research Centre, Institute for Reference Materials and Measurements, Retieseweg 111, 2440 Geel, Belgium
⁵ Porto Conte Ricerche ; SP 55 Porto Conte-Capo Caccia km. 8400 ; 07041 Alghero ( SS), Italy
⁶ Università di Roma “La Sapienza”, P.le Aldo Moro, Rome, Italy
⁷ CNRS/GEMAC, 1 Place Aristide Briand, 92190 Meudon, France
⁸ University of Verona, Department of Informatics, strada Le Grazie 15, 37134 Verona, Italy
⁹ Institute of Physics, University of Rzeszów, Rejtana 16A, 35-310 Rzeszów, Poland

^a e-mail: benjamin.robouch@lnf.infn.it

Received: 15 July 2011
Received in final form: 5 October 2011
Published online: 16 November 2011

Abstract

Similar ternary semiconductors are sometimes associated with widely different structures characterized by different site occupation preferences. We have used far-infrared (FIR) spectra to determine the site occupation preference coefficients for three ternary semiconductor alloys: ZnCdTe, ZnHgTe and CdHgTe and, in the case of ZnHgTe, have validated it by X-ray absorption fine structure (EXAFS) analysis. While ZnCdTe spectra exhibit the canonical configuration with eight phonon lines free of vibrational defect lines and only a slight departure from a random ion distribution, CdHgTe spectra show the eight canonical phonon modes plus an additional vibrational defect line and constant preference coefficients. In contrast, two defect lines and only four modes characterize ZnHgTe spectra, as extreme preferences prevent the formation of two of the five expected tetrahedral configuration arrangements. Moreover, for this system, comparison with EXAFS data points out the vibrational nature of both the extra lines. The analysis clearly shows that assuming a Bernoulli distribution of the component configurations of semiconductors may lead to wrong assessments of the evolution of its properties with relative content.