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[en] Semiconductor crystals for electronics must be defect free for best performance, but mismatches between the atomic lattice pattern of the semiconductor and the substrate, a supporting surface providing a template for the crystal being deposited on top, can cause problems. A team of researchers recently reported that a thin flexible film sandwiched between substrate and crystal can act as a buffer, absorbing the strain and allowing a wide variety of crystalline materials to be grown on the same substrate material virtually defect-free. This article discusses this recent development
[en] Single crystals of U4O4Te3, U2.67Te4 and UOTe were grown by different methods. In a sintering procedure a new uranium oxytelluride of the formula U4O4Te3 and with a tetragonal crystal structure was obtained for the first time. The growth from the melt yielded single crystals of the telluride of the chemical formula of U2.6Te4 with the Th3P4-type structure. Single crystals of tetragonal UOTe were grown by chemical transport
[en] The invention relates to the semiconductor technology in particular to the processes for semiconductor nanostructures obtaining. Summary of the invention consists in that onto one of the surfaces of a semiconducting crystals, by photolithography, it is deposited a mask, it is carried out the electrochemical picking and it is removed the mask. Novelty of the invention consists in that after removal of the mask it is additional y carried out the electrochemical picking by light irradiation, the quanta energy of which exceeds the values of the semiconductor prohibited zone
[en] In the present paper investigation results of photoluminescence of spectra doped by silicon and arsenide Ga epitaxial layers created from liquid-phase of different content are studied. Bi and Ga were used as a metals-solvent. In this case Bi and Ga contents in solution-melt are changed. Free electrons concentration at 300 K in epitaxial layers constitutes (1-3)·1017 cm -3. Photoluminescence excitation was made continuous emit time of He-Ne laser Lg-75 with length wave of λ=632,8 mm. The maximum excitation level was ∼1018 ph/cm2·s. Photoluminescence with help of focusing mirror was focused on entrance slot of monochromator MDR-23. The filter Ks-19 is installed in order to avoid scattered emittance ingress into monochromator in front of entrance slot. It is shown that photoluminescence spectra shift within longwave field with increase Bi content in solution-melt is connected with SiGa CuGa deep center formation
[en] The direct dark matter search experiment CRESST uses scintillating CaWO_4 single crystals as targets for possible WIMP recoils. A particle interaction in the crystal produces phonons as well as scintillation light. As the light signal is dependent on the kind of interacting particle, e"--recoils and α-decays mainly originating from intrinsic impurities of the crystal can be discriminated from nuclear recoils (e.g. due to possible WIMP scatterings). To achieve the best possible discrimination a high light output and a high radiopurity of the crystals are crucial. Since 2011 CaWO_4 crystals are grown in the crystal lab of TU Munich. In this way we can directly influence the growth parameters and find a method to improve light output and radiopurity which is required by CRESST and the future tonne-scale multi-material experiment EURECA. In this talk we will discuss the investigated radiopurity of the raw materials WO_3 and CaCO_3 as well as of TUM-grown crystals which are currently taking data in CRESST II Phase 2.
[en] Single crystal ingot of BiSbTeSe doped with Zr was synthesized using Bridgman method. Energy dispersive spectrometry (EDS) analysis was used to determine chemical composition of studied samples as well as to check and confirm samples homogeneity. X-ray diffraction (XRD) measurements proved that obtained crystal ingot is a single cristal and confirms Bi2Te3 -type compound with orientation (00l) of single crystal. Melting point was determined by Dilatometrically measured shrinkage during heating. Mobility, concentration, resistivity/conductivity and Hall coefficient of BiSbTeSe doped with Zr samples were determined using a Hall Effect measurement system based on the Van der Pauw method. The Hall Effect was measured at room temperature with an applied magnetic field strength of 0.37 T at different current intensities. The measured ingot samples were cut and cleaved from different regions. Calculated results obtained using a Hall Effect measurement system (Ecopia, HMS-3000) were mutually compared for cleaved and cut samples. Changing of transport and electrical parameters with the increase of the current intensity was also monitored.The results confirmed that electrical and transport properties of single crystal depend on crystal growth direction and mobility was also significantly improved in comparison with theoretical value of Bi2Te3 and available literature data.
[es]El lingote del mono cristal de BiSbTeSe dopado con Zr se sintetizó utilizando el método de Bridgman. La composición química se determinó mediante análisis con espectroscopía de dispersión de nergía (EDS). Mediante difracción de rayos X (DRX) se demostró que el lingote de cristal obtenido es un mono cristal y confirmó que se trata de un compuesto del tipo Bi2Te3 , con orientación del mono cristal (001). El punto de fusión se determinó por medidas dilatométricas. La movilidad, concentración, resistividad/conductividad, y el coeficiente de Hall del BiSbTeSe dopado con Zr, se determinaron utilizando un sistema de medición de efecto Hall basado en el método de Van der Pauw. El efecto Hall se midió a temperatura ambiente con una intensidad de campo magnético aplicada de 0,37 T a diferentes intensidades de corriente. Las muestras de lingotes medidos se cortaron y se rompieron de diferentes regiones.