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The values of optical deformation potentials (Du and Dd) for PbSe and PbTe are analyzed using absorption, luminescence and X-ray diffraction data on high quality, deep quantum well PbSe/PbSrSe and PbTe/PbEuTe structures. It is important for these evaluations to use the value of isotropic deformation potential (Diso) which is determined from the low temperature hydrostatic pressure experiments and the intervalley splitting which was determined from differential absorption spectroscopy. The fitting procedure was done using an accurate k·p model for the band structure near the fundamental gap including anisotropy, multi-valley, and band nonparabolicity effects. We find the new optical deformation potential values at 4 K: Du = - 0.2 and – 0.5 eV, and Dd = 5.3 and 3.5 eV for PbSe and PbTe, respectively.

In this work, we present the investigation of the magnetotransport properties of a capped SnTe film, grown by molecular beam epitaxy, using Shubnikov–de Haas oscillations for the detection of Dirac fermions. The cap layer used was a 10 nm thick Sn0.98Eu0.02Te film, which can also contribute to the transport such that it is mandatory to isolate its contribution from the electrical transport measured in the sample. To separate the contribution from both layers, photoconductivity measurements were performed. A detailed analysis of the Shubnikov–de Haas oscillations is carried out using theoretical expressions and building the Landau-level indexation. We found that Dirac fermions are detected in the SnTe layer, while the cap layer contributes with trivial fermions, protecting SnTe against deterioration due to exposure to the atmosphere. [ABSTRACT FROM AUTHOR]

We report here on the properties of topological crystalline insulator Pb0.5Sn0.5Te epitaxial films doped with bismuth at levels from 0% (undoped) to 0.15%. The undoped film exhibits a p-type character due to metal vacancies. As the doping level rises, the hole concentration reduces. At a level of 0.06%, the electrical character inverts to n-type and the electron density continues to increase for rising doping level up to 0.15%. This result demonstrates an effective extrinsic n-type doping of Pb0.5Sn0.5Te crystal with bismuth due to substitutional Bi atoms in metal sites. High-resolution x-ray diffraction and reciprocal space mapping show that fully relaxed high-quality films are obtained. A pristine (111) film surface is revealed after removal of the Te cover layer using a method combining Ar+ sputtering and thermal desorption. Angle-resolved photoemission spectroscopy (ARPES) data acquired at 30 K near the Γ ¯ point of the undoped film surface show a parabolic-like dispersion of the bulk valence band close to the Fermi level. Now, the ARPES data for a sample doped with 0.1% of Bi reveal that the chemical potential is shifted by 40 meV upwards in the direction of the conduction band. The ARPES results also indicate that there might be a discrepancy between surface and bulk chemical potential in the doped sample. This divergence suggests that Te atoms diffuse into the surface during the thermal process to desorb the protective layer, inverting the surface to p-type. [ABSTRACT FROM AUTHOR]

Previously, we showed that at low temperatures and very low excitation powers, EuTe displays band-edge photoluminescence with a well-resolved phonon structure, the so-called MX 0 band, which is associated with the recombination of giant spin polarons (SPs) of magnetic moments of several hundred Bohr magnetons. Here, we investigate the MX 0 band both experimentally and by Monte Carlo simulations. Results indicate that the SPs are bound to defects, with a localization energy of 0.29 eV. The density of defects harboring the SPs is estimated to be 4.3 × 10 15 cm − 3 . [ABSTRACT FROM AUTHOR]

The use of a DC glow discharge source with controlled plasma potential in plasma immersion ion implantation processing has been studied. The characteristics of the discharge source include medium densities, low temperatures, stable continuous DC operation and can be built inexpensively. A tridimensional implantation was realized when the plasma potential is held below 70 V. The plasma density of the discharge source has also been found to be linearly dependent on the potential.

Research was conducted to examine reciprocal space maps of PbTe/SnTe superlattices. To change the strain profile in the superlattices from completely pseudomorphic to partially relaxed, the individual layer thickness and number of repetitions were selected. Results demonstrate the importance of detailed structural characterization on the interpretation of electrical properties.

In this article, we report on structural and magnetic properties of cubic GaN epitaxial layers implanted with Fe ions and subsequently subjected to thermal annealing. The epitaxial quality of the layers was studied by X-ray diffraction rocking curves (ω-scans) and Raman spectroscopy. The results show that the implantation damages the crystal structure producing an expansion of the lattice parameter in the implanted region. These damages are partially removed by the thermal treatment. Room temperature ferromagnetism is observed for the sample implanted with a dose of 1.2 ×1016cm-2, while samples implanted with 2.4 ×1016 cm-2 show a coexistence of ferromagnetism and paramagnetism due to disperse Fe3+. Thermal annealing changes these magnetic properties. For the low dose sample, the ferromagnetism is converted into paramagnetism while for the high dose we observed an enhancement of the ferromagnetic contribution characterized by a super-paramagnetism behavior attributed to Fe-based particles. [ABSTRACT FROM AUTHOR]

An examination of the electrical properties of Pb1-xSnxTe epitaxial layers with Sn composition covering the whole range was conducted. Samples were grown on (111) BaF2 substrates in a molecular beam epitaxy system by PbTe, SnTe and Te solid sources. As the alloy composition varies from PbTe to SnTe, the hole concentration increases exponentially from 10 (super 17) to 10 (super 20) cubic cm for Te-rich sources and from 10 (super 17) to 10 (super 19) cubic cm for stoichiometric ones.

Kinematical diffraction theory and optical coherence formation describe the X-ray diffraction in their layers having randomly placed defects. The diffracted intensity and the angular distribution are calculated by this method. Double crystal and triple crystal X-ray diffractometry experiments are also simulated by this method. Epitaxial ZnTe layers with mosaic structures are also investigated by using this method and by the application of different steps of chemical thinning.