B. Witkowska

Band structure of β-HgS from Shubnikov–de Haas effect

Abstract The Shubnikov–de Haas oscillations were measured in zinc–blende Hg 0.98 TM 0.02 S (TM= Co, Mn, Fe) at temperatures ranging from 1.6 to 30 K, in magnetic fields up to 13 T. From standard harmonic analysis the values of the effective masses at the Fermi level versus electron concentration were determined. The analysis of this dependence within the frame of Kane model for narrow-band semiconductors yielded a low temperature value for energy gap E 0 =−0.110 eV ±0.040 eV and momentum matrix element P=7.1×10 −8 eV cm ±0.2×10 −8 eV cm .

The lattice constants of ternary and quaternary alloys in the PbTe-SnTe-MnTe system

Abstract The study of structural properties of quaternary Pb 1− x − y Sn x Mn y Te alloys revealed that they crystallise in a cubic structure of NaCl-type for a wide region of manganese content (up to y =0.16). It was found from X-ray measurements and microprobe analysis that Vegards law is obeyed. The dependencies of the lattice constants on composition for Pb 1− x − y Sn x Mn y , Pb 1− y Mn y Te and Sn 1− y Mn y Te were used to extract the lattice parameter of NaCl-type MnTe phase by extrapolation. The experimental data were also used to obtain an improved estimate of the covalent octahedral radius for Mn.

Peculiarities of transport properties in semiconductors with resonant impurities: HgSe : Fe versus PbTe : Cr

Abstract We compare the transport properties of two semiconducting systems containing resonant donors, HgSe : Fe and PbTe : Cr, with concentrations of dopants corresponding to the Fermi level being stabilized at the resonant state. It is known that under such conditions, at a low temperature, there arises a spatial correlation of electric charges localized on donor centers. The occurrence of the correlation is driven by the inter-donor Coulomb repulsive interaction. In the case of HgSe : Fe, the correlation leads to a sizable enhancement of the conduction electron mobility. In the case of PbTe : Cr, high values of the dielectric constant limit the temperature region in which the correlation is expected to occur, to temperatures below approximately 3.5 K. Therefore, no direct observation of the mobility enhancement was possible. On the other hand, a lack of a strong suppression of the mobility by the resonant scattering mechanism can be taken as an indirect indication that the positions of charged donor centers are correlated to such an extent that formation of the Coulomb gap (due to inter-donor Coulomb repulsive interaction) causes the resonant scattering to be very inefficient.

Peculiarities of the Lattice Dynamics of Cubic Mercury Chalcogenides

The lattice dynamics of cubic mercury chalcogenides (HgTe, HgSe, β-HgS) was investigated by IR reflectivity, Raman scattering and inelastic neutron scattering measurements. The important role of two-phonon Raman scattering related to TA excitations was confirmed for HgSe and β-HgS and explained by the particular TA dispersion for mercury compounds. Analysis of the optical spectra taken for HgSe demonstrates that the resonant two-phonon difference process (widely accepted for HgTe, HgSe and the mixed crystals grown on the basis of these compounds) is not able to explain the present experimental data.

Growth and Structural Characterization of Zinc Blende HgS

The zinc blende (metastable) modification of mercury sulphide was stabilized by the partial substitution of Hg atoms by Mn, Fe, and Co. The structure of such crystals grown by the modified Bridgman method was investigated by X-ray diffraction and electron transmission spectroscopy techniques. The single-phase character of the crystals was demonstrated, the presence of defects resulting from the disorder in the stacking sequence of (111) layers was evidenced.

Preparation of MnxHg1−xTe mixed crystals, x<0.2

Abstract Single crystals of MnxHg1−xTe up to x=0.2 have been grown by the Bridgman-Stockbarger technique. Methods of preparation and purification of the starting materials are described. The segregation coefficient of Mn in the investigated system was determined.

Influence of annealing on tellurium precipitates in (Cd,Mn)Te:V crystals

The authors believe that (Cd,Mn)Te can be used as a material for gamma- and X-ray detectors [1]. The investigations are concentrated on producing, by Bridgman method, of high quality (Cd,Mn)Te crystals with high resistivity (109 Ωcm).

High-pressure–high-temperature study of Hg1−xMnxS

Abstract Investigation of the sphalerite to cinnabar transition for Hg 1− x Mn x S ( x =0.02 and 0.07) is presented. The in situ high-pressure–high-temperature X-ray energy-dispersive experiments were performed using a high-volume X-ray diffraction press at HASYLAB in the p – T range 0–60 kbar and 27–600°C. At a given temperature, the transition pressure increases with the manganese content in the sample. For x =0.02, the phase transition on uploading occurs at 12.5 kbar and for x =0.07 at 24.4 kbar. The present observations are consistent with the literature data obtained at ambient pressure for samples prepared under a pressure of 18 kbar and quenched to the ambient pressure. The value of the bulk modulus for Hg 0.93 Mn 0.07 S is calculated to be 387.9 kbar.

Growth and characterization of the ternary ZnSe-based compounds obtained by low temperature vapour transport

Abstract We employed the low temperature physical vapour transport (PVT) method to grow ZnSe and ZnSe 1 − x S x ( x ≤ 0.15), high quality, large (25 mm in diameter) bulk crystals. Characterization of the obtained crystals was performed by means of X-ray diffraction, X-ray full width half maximum (FWHM) rocking curves and the energy dispersive X-ray fluorescence (EDXRF) spectrometry. Optical properties were determined from the low temperature near-band-edge photoluminescence and reflection measurements.

Technology and Characterization of Single‐Crystalline Substrates Made of ZnSe‐Based Wide‐Gap II–VI Semiconductor Compounds

Detrimental role of traces of oxygen in the growth process of the ZnSe-based wide-gap II-VI semiconductor crystals is emphasized. Adhesion, enhanced by the presence of oxygen, of the growing crystal to the walls of the quartz ampoule promotes generation of twinning and dislocations. The technology of the substrate-quality crystals, which ensures nearly complete removal of oxygen, is described. The results of characterization of the obtained large (25 mm diameter), twin-free single crystals of ZnSe, and substrate plates are presented.