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  • 1
    Electronic Resource
    Electronic Resource
    Mechanisms of molecular beam epitaxial growth of (001) HgTe (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 748-751 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on an investigation of the growth mechanisms of HgTe using a combination of reflection high energy electron diffraction (RHEED) and scanning tunneling microscopy (STM). The experiments were carried out on untilted (001) CdTe substrates. Growth rates were determined from RHEED intensity oscillations of the (00) specular spot reflection. The amplitude of these oscillations decrease with increasing substrate temperature. Above 178 °C no RHEED oscillations could be measured. Upon reducing the sample temperature below 178 °C these oscillations could again be observed. This cyclic behavior could be induced several times for each sample, indicating a reversible change in the growth mechanism. In order to correlate the surface structure with RHEED observations, several samples have been investigated with STM. Thus, it could be confirmed that a temperature dependent transition occurs during the MBE growth of HgTe from the island growth mode below the critical temperature of 178 °C to a step flow mode above this temperature. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.362682
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  • 2
    Electronic Resource
    Electronic Resource
    High-efficiency p–i–n detectors for the visible spectral range based on ZnSTe–ZnTe superlattices (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 3404-3406 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We demonstrate that ZnSTe–ZnTe superlattices, which are grown lattice matched on GaAs substrates by molecular-beam epitaxy, are well suited as a material for light detection in the visible spectral range. Due to their type-II band alignment, these superlattices have a small band gap compared to ZnSe and allow light detection for photon energies between 2.1 and 3.2 eV. In combination with ZnMgSSe, the response curve of the diodes shows a strong dependence on the applied reverse bias, so that they can be used as two-color devices. The obtained external quantum efficiencies are as high as 70%, and dark currents as low as 10−12 A/mm2 were obtained. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.123359
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  • 3
    Electronic Resource
    Electronic Resource
    Termination, surface structure and morphology of the molecular beam epitaxially grown HgTe(001) surface (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 3205-3207 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The surface structure of molecular beam epitaxially grown HgTe(001) has been studied under in situ ultrahigh vacuum conditions. The as-grown samples were investigated by means of x-ray photoelectron spectroscopy (XPS), spot profile analysis of low-energy electron diffraction, reflection of high-energy electron diffraction and scanning tunneling microscopy (STM). They exhibited a c(2×2) surface reconstruction with an additional weak (2×1) component in both diffraction experiments. The surface was shown by XPS to be terminated with Hg atoms. In addition, by means of STM experiments, we have been able to resolve the atomic structure of the reconstructed surface and to detect domain boundaries along the [11¯0] direction whose local symmetry is twofold and, therefore, the probable cause of the weak (2×1) reconstruction. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.122719
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  • 4
    Electronic Resource
    Electronic Resource
    Optimization of p-contacts on ZnSe diodes (1997)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 70 (1997), S. 1281-1283 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We show that a drastic improvement of the current voltage characteristics of a ZnSe diode can be achieved by lowering the growth temperature of a ZnSe/ZnTe multi-quantum well p contact. A similar trend is observed when the thickness of the ZnTe cap layer on top of the multi-quantum well is reduced. Both observations show that the suppression of interdiffusion plays a dominant role in the formation of Ohmic contacts to p-ZnSe. A comparison between a conventional diode and a diode where the p-ZnSe has been replaced by p-ZnSTe shows that the interdiffusion process affects the ZnSe underneath the contact, and not the multi-quantum well contact itself. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.119075
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  • 5
    Electronic Resource
    Electronic Resource
    Influence of p-type doping on the degradation of ZnSe laser diodes (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 1957-1959 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present results of optical degradation experiments on blue-green ZnSe-based diode laser structures. A micro-focused wavelength selectable laser is used for degradation and the luminescence from the degrading region is simultaneously recorded. The degradation speed at a given optical power density depends strongly on the doping of the structure and on the photon energy: undoped structures do not degrade, while the threshold photon energy to induce degradation depends on the degree of compensation in the p-doped layers. However, at high photon energies, an improvement in compensation does not slow down the degradation process, leading to the suggestion that the nitrogen acceptor itself is unstable under these conditions. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.123740
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  • 6
    Electronic Resource
    Electronic Resource
    High quantum efficiency II–VI photodetectors for the blue and blue-violet spectral range (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 3562-3564 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have fabricated II–VI wide gap hetero PIN photodiodes made of ZnMgSSe with excellent structural and interface quality and with a high external quantum efficiency of about 60%, which is close to the theoretical limit. The internal quantum efficiency reaches peak values of more than 80%. The onset of the sensitivity is very sharp, leading to a quantum efficiency less than 10−4 at wavelength 60 nm below the band gap. Using the wide range of energy gaps from 2.68 to 3.1 eV, it is possible to fabricate wavelength selective detectors if the energy gap of the top p-type layer is chosen slightly higher than that of the intrinsic zone. The dark current is below 0.1 pA/mm2. In the low signal limit, the noise equivalent power can be estimated to be below 10−15 WHz/mm2 at the peak external quantum efficiency, surpassing ultraviolet optimized Si detectors. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.122807
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  • 7
    Electronic Resource
    Electronic Resource
    Image Plates as One-Dimensional Detectors in High-Resolution X-ray Diffraction (1998)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 31 (1998), S. 446-452 
    Details
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: An image plate has been used as a detector for high-resolution X-ray diffraction of semiconductor heterostructures. A series of 2θ intensity distributions is recorded for different rocking angles ω for the sample and subsequently transformed to a reciprocal-space map. Maps of symmetric and asymmetric reflections of two samples are presented. A reduction in measurement time by a factor of 36 was achieved by recording information simultaneously along 2θ on the image plate compared to conventional measurement with a scintillation counter. Favourable results were obtained with broad reflections from samples with low structural quality and asymmetric reflections in the grazing exit geometry.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S002188989701947X
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  • 8
    Electronic Resource
    Electronic Resource
    Scanning tunneling microscope investigation of CdTe substrate surfaces for molecular beam epitaxy
    Amsterdam : Elsevier
    Journal of Crystal Growth 123 (1992), S. 42-46 
    Details
    ISSN: 0022-0248
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0022-0248(92)90008-7
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  • 9
    Electronic Resource
    Electronic Resource
    Effects of growth conditions on the surface structure of CdTe studied by a scanning tunneling microscope (1993)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 346 (1993), S. 53-57 
    Details
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary CdTe buffer layers are widely used as substrate materials for the molecular beam epitaxial (MBE) growth of Hg1−x Cd x Te because of the small lattice mismatch. With the help of a scanning tunneling microscope (STM) and a scanning electron microscope (SEM) the surface topographies of epitaxial CdTe layers grown under different conditions were studied quantitatively. It was found that photoassistance during growth enhances the formation of pyramidal hills with a typical height of 1000 Å. The use of an excess of Cd completely changes the surface morphology towards 2-dimensional growth and the remaining layer roughness was less than 50 Å. These initial results suggest that the Cd rich conditions provide a promising method for the growth of large, flat layers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00321381
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  • 10
    Electronic Resource
    Electronic Resource
    A fully computer controlled, low cost STM (1991)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 341 (1991), S. 189-192 
    Details
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary If one examines the components of a scanning tunneling microscopy system, one finds, that for a great part the computer determines the abilities of it. Once a stable mechanical setup is constructed, it depends on the control part, which features the whole system shows and how convenient one can work with it. Here we present a scanning tunneling microscope which is, as far as possible, computer controlled and can be fully operated from a user surface on the computer. This has been achieved by the use of a two computer concept. The mechanics, electronics and software were self-developed; all other components were selected under the aspect of costs resulting in a low priced and yet high performance system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00321546
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