xTe Solid Solutions Research Articles

EXAFS and 125Te spectroscopy study of the Yb 1− xEu xTe, Pb 1− xEu xTe and Yb 1− xGd xTe solid solutions

We report EXAFS (Extended X-Ray Absorption Fine Structure) measurements on three solid solutions of rare-earth monotelluride in order to measure the x-dependence of the cation-anion distance and Debye-Waller factor. We find Yb 1− x Eu x Te is an ideal solid solution with a bimodal distribution of distances, accommodated by the Te sublattice, at contrast with the two other solid solutions Pb 1− x Eu x Te and Yb 1− x Gd x Te. The anomalous behaviour of the EXAFS parameters in the last system is related to the shallow nature of the Gd donor.

Study of the magnetic properties of the La 1− xGd xTe solid solution

We present a study of the physical properties of the La 1− x Gd x Te solid solution. Although both LaTe and GdTe crystallize in the fcc structure and are metallic, two domains in the x-dependence of the lattice parameters of their solid solution can be distinguished. At the critical concentration, no anomalies in the magnetic susceptibility or the electrical resistivity can be detected. Both the Néel and paramagnetic Curie temperatures are linearly x-dependent, at x ≥ 0.5, with opposite slopes. The results are discussed within a molecular field treatment of the RKKY exchange interaction in which the disorder generated by spin dilution is averaged out.

Surface States of Laser-Irradiated Cadmium- and Tellurium-Containing Solid Solutions of II-VI Compounds

Equilibrium conductivity and photoconductivity (PC) of MgxCd1−xTe (T = 300 K) and the PC and photomagnetic effect (PME) of CdxHg1−xTe (T = 77 K) solid solutions (SS) before and after irradiation with ruby laser pulses in the Q-switched mode are analyzed. Laser irradiation is shown to increase the forbidden gap width and to change the stoichiometric composition in the subsurface region of the SS. In n-type MgxCd1−xTe crystals a donor-enriched layer is formed and a Te film appears on the surface; in n-type CdxHg1−xTe crystals a conductivity-type inversion occurs and a built-in p–n junction arises under the action of laser emission pulses. [Russian Text Ignored].

Erratum - Optical vibration modes in Hg1- xZn xTe solid solutions near q = 0.

Erratum - Optical vibration modes in Hg1- xZn xTe solid solutions near q = 0.

Composition dependence of thermal vibrations in Hg 1−xZn xTe solid solutions determined by X-Ray diffraction

We report on the composition dependence of thermal vibrations in Hg[in1- xZn x Te solid solutions ( x = 0.13,0.20, 0.50, 0.75) determined by X-ray diffraction at room temperature (297 K) and in some cases ( x = 0.50, 0.75) at 143 K. Although some ambiguity on the results obtained for x ≅ 0.50 cannot be avoided as being intrinsic to the problem, it is shown, by taking into account the results obtained by Cooper, Rouse and Fuess Acta crystallogr. A29, 1973 on ZnTe ( x = 1), that the conventional harmonic B factor ( B = 8 π 2〈 u 2〉 where 〈 u 2〉 is the mean-square displacement of the atom in any direction) of the average (HgZn) cation decreases almost linearly from B Hg- Zn = 2.82 ( σ = 0.09) Å2 to B jn = 1.296 ( σ = 0.034) Å 2 when x varies from x = 0.13 to x = 1. This is interpreted as resulting from the almost composition independent B Hg ≅ 2.7 Å 2 and B Hg ≌ 1.3 Å 2. By contrast the B factor of the Te anion exhibits a more complex behaviour varying in a non-monotonic way from 2.03 (σ = 0.07) Å 2 for x = 0.13 to 0.76 ( σ = 0.01) Å 2 for x = 1. In the alloys the B factors do not vary linearly with T between 297 and 143 K. It is shown that this is not attributable to quantum effects (zero point motion) but is due to a static structural disorder which affects the metal as well as the anion sublattices, the average atomic distortion being about 0.08 Å. The experimental data also show contributions arising from third-order anharmonic thermal vibrations of the atoms.

Electron irradiation influence on the thermoelectric and galvanomagnetic properties of the CdxHg1-xTe solid solutions

Abstract The thermoelectric and galvanomagnetic properties in the CdxHg1_xTe solid solution samples (x = 0.12; 0.15) irradiated at 300 K by electrons (3.5 MeV; by integrated fluxes up to 1.46 × 1018e/cm2) have been investigated in a wide temperature range 4.2–300 K and in magnetic fields 0–22 kOe. It has been discovered that the electron irradiation of CdxHg1–xTe crystals leads to an increase of the Hall coefficient and a decrease of the thermo e.m.f. sign inversion temperature. The concentrations and mobilities of electron and hole have been calculated on a basis of quantitative analysis of galvanomagnetic data. It has been shown that the kinetic coefficient behavior upon irradiation is due to the Te vacancy-based type radiation defect origin.

Growth of thin films of Cd xHg 1− xTe solid solutions by cathodic sputtering in a mercury vapour plasma

A study of the formation of films of Cd x Hg 1− x Te solid solutions by sputtering in a mercury vapour plasma was carried out. The condensation rate and the condensed material composition were investigated experimentally as functions of the main sputtering parameters, namely the sputtering pressure, the substrate temperature, the sputtered fluxes, the target voltage and the bias voltage. The role of the mercury vapour pressure was determined, as well as the conditions of formation of single-phase or two-phase films. The study of condensed fluxes and condensation coefficients of cadmium and tellerium atoms contributed to the understanding of the growth process.

Crystal growth of ZnxCd1−xTe solid solutions and their optical properties at the photon energies of the lowest band-gap region

Single crystals of ZnxCd1−xTe solid solutions have been grown from a melt under an Ar pressure of about 50 atm. The crystals of uniform composition were grown over the whole range of molar composition, when the crystal growth was performed in excess Zn and/or Cd. A grown boule of 30 × 15 mm φ contained several single-crystal domains of size 7 × 5 × 5 mm. On the basis of Vegard's law, the molar composition x was determined from x-ray measurements of lattice constants. The variation of x throughout a single-crystal domain was found to be less than ± 1%. Optical experiments including transmittance and reflectance measurements have been made on the cleaved (110) planes at room temperature. The variation of the lowest band gap with x was determined from the peak positions in the reflectivity spectra. The bowing parameter, which is a measure of the deviation from the linear change, of this gap was found to be 0.33 eV.

On the Thermal Conductivity of ZnxHg1−xTe Solid Solutions

AbstractThermal conductivity measurements are carried out in single crystals of ZnxHg1−xTe solid solutions as a function of composition and temperature between 90 and 450 °K. The temperature dependence of the thermal conductivity in ZnTe may be explained by U‐processes. At the same time, the lattice thermal conductivity measured in these solid solutions is lower than that calculated on the basis of U‐processes and phonon scattering at point defects. Therefore it is assumed that the interaction between acoustical and optical phonons as well as the three‐phonon N‐processes also contribute to the thermal resistivity in these solid solutions. In the light of this assumption, a satisfactory agreement is found between the experimental and the calculated values of the lattice thermal conductivity.