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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 3630-3634 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Electron-beam (EB)-induced pattern etching of AlxGa1−xAs (0≤x≤0.7) is described. An ultra-thin GaAs oxide at the surface of a GaAs/AlGaAs heterostructure wafer is used as a resist film. The GaAs oxide resist can be selectively removed by EB irradiation in a Cl2 ambient, which results in pattern etching of GaAs/AlGaAs. The etch rate of AlGaAs is examined as functions of substrate temperature, AlAs mole fraction, and EB flux. The results indicate that pattern etching is realized in the AlAs mole fraction range of 0≤x≤0.7
    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 68 (1990), S. 2392-2399 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Damage in GaAs induced by Ga+ focused-ion-beam-assisted Cl2 etching is studied by photoluminescence (PL) intensity measurements as functions of ion energy, ion dose, and substrate temperature. By decreasing the ion energy from 10 to 1 keV, the damage depth decrease to 1/5, where damage depth is taken as the thickness at which the PL intensity recovers by wet etching. The damage depth is shallower when the etching yield is larger with the same ion energy. By increasing the ion dose, the normalized PL intensity decreases, but damage depth is nearly constant. Over 1015 ion dose, the normalized PL intensity shows a constant value. By increasing the sample temperature, the damage depth becomes shallower. At 150 °C with ion energy of 1 keV, the damage depth is less than 0.5 μm, which is the detection limit of the PL measurement in GaAs substrate.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 6415-6419 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Pattern formation on GaAs by Ga+ focused-ion-beam (FIB) irradiation and subsequent Cl2 gas etching was carried out. A higher etch rate at the FIB-irradiated area compared with that not irradiated under Cl2 gas allows pattern construction without a mask process. The degree of residual crystal damage was evaluated using photoluminescence (PL) intensity measurements. The PL intensity in the etched region was one order of magnitude stronger than that of FIB sputtering, and was several times stronger than that of Ga+ FIB-assisted Cl2 etching. Etch depths of the order of 100 nm, which is five times deeper than that obtained by FIB sputtering, were efficiently performed using moderate Ga+-ion doses.
    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 67 (1990), S. 4297-4303 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The first demonstration of in situ electron-beam (EB) lithography is reported, where a photo-oxidized surface thin layer of GaAs is used for a resist. The in situ EB lithography sequence consists of five processes, i.e., preparation of a clean GaAs surface, photo-oxidation for a resist film formation, direct patterning of the oxide resist by EB-induced Cl2 etching, Cl2 gas etching of GaAs surface for pattern transfer, and thermal treatment in an arsenic ambient for resist removal and surface cleaning. The GaAs wafer is never exposed to air throughout all of the above processes to avoid an unintentional surface contamination. The minimum electron dose required for patterning of the GaAs oxide resist is about 5×1016 cm−2. An overgrown layer on the patterned GaAs surface shows a good surface morphology, which strongly indicates that this technology makes it possible to repeat crystal growth and surface patterning.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 56 (1990), S. 98-100 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: This is the demonstration of "in-situ masking'' concept. In situ patterning of GaAs is carried out by using a photo-oxidized surface layer as a mask for subsequent Cl2 etching. Clean GaAs surface provided by molecular beam epitaxy is exposed to pure oxygen and is simultaneously irradiated with an Ar+ ion laser of the 514.5 nm line for photo-oxidation of the surface. Subsequent Cl2 gas etching of the photo-oxidized sample reveals that the GaAs oxide fills the role of an etching mask. The resistance of the oxide mask against Cl2 etching varies depending on the laser fluence with which the oxide of GaAs is formed.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 57 (1990), S. 1012-1014 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Pattern etching of GaAs at submicron size is carried out by in situ electron beam (EB) lithography using a computer-controlled pattern generator. GaAs oxide on the wafer surface is used as a resist film in EB-induced Cl2 etching. A 0.5 μm linewidth in a 1 μm pitch line-and-space pattern with flat top surface is obtained. Observations of the pattern edge with a scanning electron microscope show that the boundary between the etched area and the oxide mask area is abrupt and that the undulation of the pattern edge is less than about 30 nm.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 16 (1969), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract— —An enzyme catalysing the transfer of sulphate from 3′-phosphoadenylsulphate to serotonin was purified from rabbit brain. The purification procedure involved ammonium sulphate fractionation of the 200,000 g supernatant of rabbit brain homogenate, treatment with alumina Cγ, and chromatography on DEAE-cellulose. The enzyme was purified 67-fold from the 200,000 g supernatant of the brain homogenate. The intracranial distribution of the sulphotransferase was investigated and the cerebellum found to have rather high activity. The sulphotransferase activities of rabbit, dog, rat and bovine brains were compared; rabbit brain had the highest activity, followed by dog, rat and bovine brain.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 60 (1992), S. 365-367 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Buried GaAs/AlGaAs single quantum-well structures have been fabricated for the first time by in situ electron beam (EB) lithography. The process includes the molecular beam epitaxy of a GaAs/AlGaAs single quantum well, electron-beam direct writing, Cl2 gas etching, and overgrowth of an AlGaAs layer. A thin GaAs oxide layer was used as the etching mask, which was selectively formed on a clean GaAs surface by EB irradiation under an O2 ambient. Subsequent Cl2 gas etching resulted in the formation of isolated quantum wells. Prior to the overgrowth, thermal cleaning with atomic hydrogen was employed for removing the oxide mask. The cathodoluminescence image of the buried quantum well demonstrates the high quality of the resultant structure formed by in situ EB lithography.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Pharmacology 32 (1992), S. 377-397 
    ISSN: 0362-1642
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Medicine , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 36 (1980), S. 880-882 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 14C labelled iproniazid binds to iodide peroxidase more effectively in low ionic strength buffer than in high ionic strength buffer, suggesting preferential binding to the monomeric form of iodide peroxidase. During column chromatography, under conditions that separate iodide peroxidase into multiple forms, iproniazid is bound selectively to the monomeric form. Thus, this antithyroid agent appears to bind preferentially to the monomeric enzyme form, or possibly to cause dissociation of the polymeric to the monomeric form.
    Type of Medium: Electronic Resource
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