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.
Ion distribution preferences in ternary crystals ZnxCd1-xTe, Zn1-xHgxTe and Cd1-xHgxTe / B. V., Robouch; I. V., Kutcherenko; M., Cestelli Guidi; A., Kisiel; A., Marcelli; P., Robouch; M., Piccinini; Nucara, Alessandro; R., Triboulet; E., Burattini; J., Cebulski; E. M., Sheregii; J., Polit. - In: THE EUROPEAN PHYSICAL JOURNAL. B, CONDENSED MATTER PHYSICS. - ISSN 1434-6028. - STAMPA. - 84:2(2011), pp. 183-195. [10.1140/epjb/e2011-20575-1]
Ion distribution preferences in ternary crystals ZnxCd1-xTe, Zn1-xHgxTe and Cd1-xHgxTe
NUCARA, Alessandro;
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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
