1,720,993 research outputs found
Si(111) and Si(100) surfaces observed in air by scanning tunneling microscopy
No full textSi(111) and Si(100) surfaces have been observed by an air-operating scanning tunneling microscope (STM). On the cleaved Si(111) surface STM topographic images show predominantly [211BAR]-oriented monatomic steps. The distribution of the width of the terraces is centered around 4 nm. Si(100) surfaces have been hydrogen-terminated by a treatment with fluoridic acid (HF). The surface appears in the topographic STM images to be quite stable and smooth with presumably no oxide
Fault Diagnosis in VLSI IC's by Simultaneous use of Scanning Electron and Tunneling Microscopy
No full textActivated chemisorption of oxygen on Si(111)-2x1
No full textResults on the chemisorption of molecular oxygen on Si(111)-2x1 at different temperatures are reported. They show that oxygen is initially physisorbed in a precursor state, From which it can be thermally activated into the chemisorbed slate. An activation energy of 20 meV is found. The dependence of the sticking coefficient upon coverage deviates from the classical Langmuir theory. A model of chemisorption fitting the experimental observations is presented. In the frame of this model, the heights of the barriers for chemisorption and desorption are obtained
Dielectric functions of Si(111)2×1, Ge(111)2×1, GaAs(110) and GaP(110) surfaces obtained by polarized surface differential reflectivity
No full textWe present a determination of surface dielectric functions (SDF) of Si(111)2×1, Ge(111)2×1, GaAs(110) and GaP(110) surfaces obtained using polarized surface differential reflectivity (SDR) technique. © 1987 Elsevier Science Publishers B.V. (North-Holland Physics Publishing Division)
Study of early stages of diamond nucleation and growth by combined use of SEM and AES techniques
No full textIn this work we present a characterization by Auger electron spectroscopy (AES) and scanning electron microscopy (SEM) of diamond surfaces, prepared with the technique of chemical vapour deposition (CVD). The initial nucleation of diamond has been studied on Si(111) substrates exposed to hydrocarbons for 5 and 20 min. The lineshape of carbon Auger transition together with SEM observation seem to show evidence of the presence of diamond nuclei on the sample after 5 min of growth and a continuous film on the sample after 20 min without any other carbon phase (noncrystalline or highly disordered carbon phase)
Imaging of single‐stranded DNA with the scanning tunneling microscope
No full textUncoated single-strand DNA mixed with BAC (benzyldimethylalkylammonium chloride) were deposited on gold substrates and imaged in air with the use of a high-resolution scanning tunneling microscope (STM). Constant-current and gap-modulated STM images showed both double- and single-stranded DNA. Along the single DNA backbone we have, tentatively, assigned small structures to phosphate and sugar group components; bumps aside single filaments, that correspond, presumbaly, to the bases DNA, have sometimes been observed
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Surface proximity effects in III-V quantum wells investigated by photoreflectance
No full textPhotoreflectance spectroscopy (PR) of In0.1Ga0.9As/GaAs and Al0.3Ga0.7 As/GaAs near-surface quantum wells has been investigated to determine the influence of the quantum well on the surface potential. In the regime of carriers tunneling from the quantum well to surface states, the PR signal from the well decreases, until vanishing when tunneling dominates over radiative recombination in the well. This result suggests that a quantum well next to the surface has the effect of creating a nearly fiat band condition in a region comprehensive of the surface and the well itself
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