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  • 1
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 56 (1990), S. 1311-1313 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Etching of SiO2 with low-energy Ar ions has been studied in an electron cyclotron resonance (ECR) based etching system. Ion energies were controlled by a capacitively coupled 13.56 MHz bias of the substrate. Etch rates of over 100 A(ring)/min have been achieved at ion energies below 100 V. The variation in etch rate has been studied as a function of ECR power, self-induced bias, and position of the wafer relative to the ECR source. This low-energy process can be utilized for cleaning of semiconductor surfaces prior to chemical vapor deposition or metallization processes.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 51 (1987), S. 1083-1085 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The use of a reactive ion etch process with high selectivity for etching GaAs layers and stopping on underlying AlGaAs layers is reported. A key feature is the high degree of control that can be maintained over the GaAs-to-AlGaAs selectivity by changing the SF6/SiCl4 ratio while keeping other etch parameters such as pressure, dc bias, or power constant. Values of the GaAs-to-AlGaAs selectivity can be varied from 1 to 500. Diluent gases such as helium can be added to reduce the etch rate, which is important to avoid damage to sensitive device structures and to the overhang profile of resist materials used for liftoff metallization. The application of this etch process for high electron mobility transistor fabrication is discussed.
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  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 51 (1987), S. 2225-2226 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Reactive ion etching is important for III-V device fabrication. Commonly encountered applications include the need to remove an epitaxial layer selectively from underlying layers and the need for definition of mesas and other structures with carefully controlled dimensions. We present results showing the use of very thin Al0.9Ga0.1As and In0.2Ga0.8As stop-etch layers, which when used in conjunction with a particular etch chemistry can provide highly selective removal of epitaxial layers in GaAs-based III-V compound semiconductors. In addition, we report the selective removal of an Al0.3Ga0.7As layer from underlying GaAs by the use of a thin In0.2Ga0.8As interlayer.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 60 (1986), S. 800-802 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The generation of slip dislocations in BF2 ion-implanted, 100-mm-diam silicon wafers during rapid thermal annealing is investigated. Whole wafer x-ray topography shows that annealing at 1150 °C causes slip to initiate randomly at positions of maximum resolved stress at the wafer edges and over scribe marks made on the back surface prior to annealing. Lowering the annealing temperature by 20 °C, which corresponds to decreasing the silicon yield stress by less than 106 dyn cm−2, prevents slip from occurring and allows sufficient removal of implantation-induced defects from which junction diodes with good current-voltage characteristics are fabricated.
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  • 5
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 60 (1992), S. 1444-1446 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A novel technique was developed to grow high-purity polycrystalline diamond films at 850 °C and 50 mTorr with 10% CH4, 2% O2, and balance H2 using a filament-assisted chemical vapor deposition technique in combination with an electron cyclotron resonance (ECR) plasma. Using Raman spectroscopy and in situ plasma diagnostics, we have shown that the hydrogen plasma selectively etched nondiamond components during deposition. Experiments with ECR plasma and the filament-assisted technique from 10−6 Torr to 50 mTorr and 500–1000 °C indicated that low-energy electrons are a key factor in growth of diamond thin films.
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  • 6
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 67 (1995), S. 1393-1395 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Strained In0.21Ga0.79As/GaAs quantum well structures have been grown by molecular beam epitaxy on (111)B GaAs substrates. Well widths between 20 and 160 A(ring), separated by 500 A(ring) barriers were grown sequentially on the same substrate and subsequently characterized by low-temperature (10 K) photoluminescence. The variation of the e-hh transition energy with well width is markedly different for samples grown simultaneously on (100) and (111)B substrates due to the strain induced piezoelectric field. Using the envelope function approximation, the dependence of n=1 e-hh transitions of (111)B samples on well width can be interpreted by the presence of a built-in electric field of magnitude of 1.45×107 V/m. In contrast to the (100) sample, exciton lifetimes in the (111)B sample depend strongly on well width because of spatial separation of electrons and holes in the triangular wells. In the 160 A(ring) well, the exciton lifetime increases to 755 ns corresponding to a reduction of about three orders of magnitude in the electron-hole wave function overlap integral. © 1995 American Institute of Physics.
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  • 7
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 1039-1041 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 74 (1962), S. 879-879 
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 9
    ISSN: 0730-2312
    Keywords: IL-3-dependent FDC-P1 cells ; histone H4 gene ; cell cycle control ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: To evaluate transcriptional mechanisms during cytokine induction of myeloid progenitor cell proliferation, we examined the expression and activity of transcription factors that control cell cycle-dependent histone genes in interleukin-3 (IL-3)-dependent FDC-P1 cells. Histone genes are transcriptionally upregulated in response to a series of cellular regulatory signals that mediate competency for cell cycle progression at the G1/S-phase transition. We therefore focused on factors that are functionally related to activity of the principal cell cycle progression at the G1/S-phase transition. We therefore focused on factors that are functionally related to activity of the principal cell cycle regulatory element of the histone H4 promoter:CDC2, cyclin A, as well as RB-and IRF-related proteins. Comparisons were made with activities of ubiquitous transcription factors that influence a broad spectrum of promoters independent of proliferation or expression of tissue-specific phenotypic properties. Northern blot analysis indicates that cellular levels of cyclin A and CDC2 mRNAs increase when DNA synthesis and H4 gene expression are initiated, supporting invoulvement in cell cycle progression. Using gel-shift assays, incorporating factor-specific antibody and oligonucleotide competition controls, we define three sequential periods following cytokine stimulation of FDC-P1 cells when selective upregulation of a subset of transcription factors is observed. In the initial period, the levels of SP1 and HiNF-P are moderately elevated; ATF, AP-1, and HiNF-M/IRF-2 are maximal during the second period; while E2F and HiNF-D, which contain cyclin A as a component, predominate during the third period, coinciding with maximal H4 gene expression and DNA synthesis. Differential regulation of H4 gene transcription factors following growth stimulation is consistent with a principal role of histone gene promoter elements in integrating cues from multiple signaling pathways that control cell cycle induction and progression. Regulation of transcription factors controlling histone gene promoter activity within the context of a staged cascade of responsiveness to cyclins and other physiological mediators of proliferation in FDC-P1 cells provides a paradigm for experimentally addressing interdependent cell cycle and cell growth parameters that are operative in hematopoietic stem cells. © 1995 Wiley-Liss, Inc.
    Additional Material: 9 Ill.
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  • 10
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A major part of current effort in improving artificial hemodialysis techniques concerns the development of improved membrane structures. Although blood compatibility of membranes is a part of the Battelle program, this discussion is confined to membrane composition, structure, and transport. On the basis of a need for improved hemodialysis techniques, membranes for use in the artificial kidney were prepared and evaluated for urea, creatinine, and uric acid permeability. Water-soluble polymers were crosslinked to form insoluble, but swellable, membranes. Faster metabolic waste transfer than with the conventional cellulosic membranes was obtained with diisocyanate-crosslinked poly (vinyl pyrrolidone) and poly (vinyl pyrrolidone)-dextran membranes and with membranes obtained by crosslinking poly (vinyl alcohol) with polyfunctional aldehydes. Membranes prepared from emulsions of vinyl pyrrolidone-ethyl acrylate and vinyl pyrrolidone-styrene copolymers had exceptionally high urea and creatinine dialysis rates, but were deficient in uric acid transfer. This shortcoming was corrected by incorporating solutes such as sucrose into the membranes followed by leaching. Another important approach concerned the development of a relatively high-strength membrane based on an impermeable nylon resin. Permeability of these membranes which have dialysis characteristics superior to those currently used was obtained through the addition of DMSO and one of several other additives to the coating solution.
    Additional Material: 1 Ill.
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