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  • 1
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 216-225 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Transverse resistivity ρxx, longitudinal resistivity ρzz, and Hall resistivity ρxy on heavily indium-doped as-grown and annealed Hg1−xCdxTe (0.24〈x〈34) alloys in a magnetic field up to 12 T and temperature range 1.2–25 K have been measured. The as-grown and annealed samples show good quality Shubnikov–de Haas oscillations in which the effective masses m*, free-electron densities nSdH, and Dingle temperatures TD are extracted. The deduced m* and nSdH from the as-grown and annealed samples are in good agreement within 12%. However, there are considerable improvements in the low field Hall mobility μH (a maximum 54% increase) and a reduction in TD (a maximum 65% decline) in the annealed samples. Analysis at low field seems to indicate that broadening due to an inhomogeneous impurity distribution contributes to TD in addition to the partial cancellation produced by different frequencies of oscillations. An estimate of the average values of an electron density fluctuation Δn/n and its spatial extent ΔL based only on TD and Hall mobility temperature Tμ is presented. The deduced ΔL is in the order of mean free path l. This, therefore, can limit μH and the values of l and ΔL and this indicates that if there is an inhomogeneous distribution of indium donor, high-temperature annealing tends to homogenize the distribution of indium donors by diffusion.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 1879-1881 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: CdTe has been grown on Si(100) by molecular beam epitaxy. Two orientations can be obtained: (111)B CdTe when the CdTe is deposited directly on the Si(100) substrates, and (100)CdTe when an intermediate layer of ZnTe is grown first. The (111)B oriented layers are made of two domains which are rotated by 90°. A layer with only one domain can be grown on Si(100) misoriented by 8°, but the best misorientation for this purpose still needs to be found. These layers were characterized by reflection high-energy electron diffraction, photoluminescence spectroscopy, scanning electron microscopy, and x-ray diffraction. Hg1−xCdxTe has also been grown by molecular beam epitaxy on (111)B CdTe on Si(100).
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 56 (1990), S. 1266-1268 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have used deep level photoluminescence spectroscopy to investigate the surface electronic quality of molecular beam epitaxy (MBE) grown CdTe layers during ultrahigh vacuum cleaning. Spectra are highly sensitive to heat treatment, contamination, and electron beam exposure. The technique provides a guide to growth and cleaning of MBE films of optimal electronic quality, which exhibit intense near-band-edge and minimal deep level emission and which exceed substantially the electronic quality of bulk CdTe crystals.
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 4003-4010 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In previous papers, a new model was proposed for the optical dielectric function of zinc blende semiconductors and was applied successfully to the alloy series AlxGa1−xAs. It was found to be more generally valid than any previous model. In this paper, it is used to obtain an analytic expression for the dielectric function of the II-VI compound CdTe at room temperature. Unlike the previous application, additional polynomial terms in the real part of the optical dielectric function are not introduced, so that the Kramers-Kronig relationship between the real and imaginary parts of the dielectric function is satisfied exactly. As demonstrated before, the model covers not only the entire photon energy range of the given spectral data, but also is valid below and somewhat above the given spectral range. This is advantageous especially when spectral data are not provided in the range of interest, or when joining two separate data causes an artificial discontinuity. The model determines the optical dielectric function in the limit as the line broadening approaches zero, which is useful in calculating the optical dielectric function at all temperatures. For demonstration, the optical dielectric function at 70 K and 600 K is calculated and presented. © 1995 American Institute of Physics.
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 1096-1099 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: It is difficult to extract unique values of the Hall electron density, nH, and Hall mobility, μH, in indium-doped Hg1−xCdxTe alloys usually in a region of weak magnetic fields where the Hall coefficient RH behaves anomalously. Since this is also the field region where the weak magnetic field condition of semiclassical transport equations is valid, derivatives of Hall resistivity ρxy(B) and the ratio (Hall angle) of ρxy(B) and transverse resistivity ρxx(B) with respect to the field are used to determine unique values of the weak magnetic field nH and μH. This analysis reduces to calculating the slopes of ρxy(B) and ρxy(B)/ρxx(B) in the region of weak magnetic fields where linearity is observed. The conductivity, σ0, determined from the ratio of the slopes is compared to the zero magnetic-field experimental value. The conductivities agree to within 10%, indicating that nH is constant in contrast to the RH result. The values of nH determined from the slopes are in very good agreement with the values of nH determined from a high magnetic field RH and from the period of Shubnikov–de Haas oscillations in heavily doped alloys.
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 1005-1009 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the recombination mechanisms of minority carrier lifetime in indium-doped layers of (211)B Hg1−xCdxTe(x ≈ 23.0% ± 2.0%)n-type grown by molecular beam epitaxy. Measured lifetimes were explained by an Auger limited band-to-band recombination process in this material, even in the extrinsic temperature region. Frequently, in some of the layers, a combination of the band-to-band recombination mechanisms together with recombination at the Shockley–Read single level 33 to 45 meV below the conduction band was necessary to explain the measured data. Results indicate that these defects have acceptorlike characteristics and their origin is related to Hg vacancies.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 52 (1988), S. 2151-2153 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: p-n junctions have been fabricated, using the ion implantation technique, on a Hg1−xCdxTe epilayer grown by molecular beam epitaxy (MBE) on a CdTe(111)B substrate. These junctions have been made on as-grown p-type layers, 12 μm thick. The layer (x=0.34) exhibits at 77 K a hole mobility of 800 cm2 V−1 s−1 and a carrier concentration of 3.6×1015 cm−3. The diode dark currents in the diffusion regime and the spectral response attest to the excellent uniformity in composition of the layer. We have also established that in the diffusion regime the data can be explained by the ideal diode equation with electrical parameters measured on the as-grown MBE layers. We consider this an important step in the understanding of the relationship between material parameters and device performance.
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  • 9
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A photoconductor array was made using molecular-beam epitaxy (MBE) grown CdTe. CdTe has been found to be an excellent material for high-energy photon detection. The objective is to develop an array detector with high efficiency and fast response toward x rays. There is considerable interest in the development of new x-ray detectors for use in the new synchrotron-radiation sources. Photoconductor arrays with gaps ranging from 5 to 50 μm between elements and 100 μm pitch size have been fabricated. The temporal response of the detectors was measured using 100 fs Ti:sapphire laser pulses. The temporal response of the photoconductor arrays is as fast as 21 ps rise time and 38 ps full width half maximum (FWHM). Spatial and energy responses were obtained using x rays from rotating anode (ANL) and synchrotron-radiation sources (NSLS, beam line X-18 B). The spatial resolution of the photoconductor obtained was 75 μm FWHM, for a 50 μm beam size. The best results were obtained for those arrays with the best crystal qualities. Linear response up to an energy of 15 keV was observed. Also observed was that a substantial number of x-ray photons were effectively absorbed within the MBE CdTe layer. The array detector did not show any evidence of radiation damage after x-ray exposures of several days. When the detector is cooled to 230 K the signal-to-noise ratio is improved by more than an order of magnitude. These results demonstrate that MBE grown CdTe is a suitable choice to meet the detector requirements for synchrotron-radiation applications. © 1995 American Institute of Physics.
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  • 10
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 84 (1998), S. 4292-4299 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A comprehensive view of the microstructure of (111)B CdTe films grown on miscut (001)Si substrates by molecular beam epitaxy has been obtained by transmission electron microscopy and scanning transmission electron microscopy. It is found that in the initial growth stage, CdTe nucleates with a dominance of one particular domain: a domain with (111)B polarity and orientation of [11−2]CdTe//[1−10]Si, although there are also some other domains of different polarity and orientation. The dominance of one type domain is due to the reduction of the surface symmetry by using the miscut substrate and by using optimum growth conditions. As the growth proceeds, a single-crystal film is produced by the dominating domain overgrowing the minority domains nucleated at the film–substrate interface. This results in the final film of single-crystal character having (111)B polarity with [11−2]CdTe along [1−10]Si. © 1998 American Institute of Physics.
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