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  • 1
    Electronic Resource
    Electronic Resource
    The lattice locations of silicon atoms in delta-doped layers in GaAs (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 633-639 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have used secondary ion mass spectrometry, local vibrational mode infrared absorption, and electrical characterization to study the incorporation of Si delta-doped planes in GaAs grown by molecular beam epitaxy at 400 °C, in the concentration range 0.01–0.5 monolayers. A correspondence is observed between the density of SiGa donors, the free electron concentration and the total Si coverage, up to a coverage of ∼1013 cm−2; however, above this value, the electron density falls, while [SiGa] remains constant up to a coverage of ∼1014 cm−2, and then falls below the detection limit at 0.5 monolayer coverage. These effects have been interpreted in terms of a model which takes account of Si migration and aggregation on the delta-doped plane during deposition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.353374
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  • 2
    Electronic Resource
    Electronic Resource
    Profile distortions during secondary ion mass spectrometry analyses of resistive layers due to electron stimulated desorption and charging (1986)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 60 (1986), S. 2573-2579 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The problem of charge compensation during SIMS depth profiling of resistive-layer structures on insulating substrates is discussed with reference to BF2 and As-implanted silicon-on-sapphire (SOS). Accurate positive ion fluorine profiles (from the BF2 in SOS samples) could not be obtained using electron beam charge compensation, due to an intense electron stimulated desorption (ESD) signal at mass 19. This species is shown to be F+. Evaporation of a gold-surface-edge electrode, 50 nm thick, represents an alternative charge compensation technique, providing a conduction path from crater edge to sample holder that bypasses the insulating substrate. Fluorine profiles can thus be obtained to within a few hundred angstroms of the sapphire. Such an electrode may be of more general use as it simplifies the setting up of electron beam charge compensation, where profiles are to be taken through a conductor and into an insulator, facilitating correct charge compensation at both sides of the interface. Accurate arsenic profiles (from the As in SOS samples) also require careful charge compensation, particularly in quadrupole based machines. Small changes in surface potential can lead to the illusion of dopant pile up (at an interface, for example) as Si2O is swept into the bandpass of the instrument. It is demonstrated that the intercomparison of mass channels, tuned to the same mass but different starting potentials, is an invaluable aid in the detection of such artifacts. The comparison of matrix-channel-ion images obtained at different stages in the profile is also useful and shows that the charging of the crater base does not occur uniformly.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.337123
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  • 3
    Electronic Resource
    Electronic Resource
    Thermodynamic considerations of metal halide vapour complexes (1985)
    Springer
    Journal of materials science 20 (1985), S. 449-456 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Certain metal halide vapour complexes of the type ABX m+n increase the equilibrium vapour concentration of one or both of the component salts in the binary system (AXm/BXn). Such enhancement depends upon the free energy of complex formation, the saturated vapour pressure of the complexing salt and the melt activities, in a manner formulated here by means of a thermodynamic scheme. Certain trends in the periodic table are established.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01026513
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  • 4
    Electronic Resource
    Electronic Resource
    Metal halide vapour complexes: vapour transport and lamp experiments (1985)
    Springer
    Journal of materials science 20 (1985), S. 457-466 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Stable vapour complexes of the type ABX m+n can sometimes increase the vapour concentration of a low volatility salt above the liquid pool. If the equilibrium concentration of A and/or B, in all their molecular forms above the binary melt AX m /BX n exceed their values above their respective pure salts enhancement (F〉1) has occurred. Mass spectrometric data suggests that such enhancement may occur in two dissimilar systems NaCl/ PbCl2 (F Na〉1) and NaCl/DyCl3 (F Dy〉1). Vapour transport and electrical discharge lamp experiments have been used to test this prediction by direct measurement of the enhancement and the results are reported here.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01026514
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  • 5
    Electronic Resource
    Electronic Resource
    SIMS analysis of Al δ-doped GaAs test structures using chemical bevelling as a sample preparation technique (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 23 (1995), S. 665-672 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A chemical bevelling technique has been developed to synthesize high-magnification bevels in gallium arsenide for SIMS linescanning and imaging. Bevels have been prepared in gallium arsenide substrate material, in gallium arsenide implanted with aluminium and in two delta-doped (aluminium) GaAs test structures. The accuracy, sensitivity, dynamic range and depth resolution-depth characteristics of the bevel and linescan approach have been compared to conventional SIMS depth profiling. Images of the bevelled structures have been used to obtain a quick view of the features of interest. Linescans have yielded an aluminium profile from the aluminium implant that is very similar to that from a SIMS depth profile. Linescan results from the aluminium deltas in gallium arsenide indicate that depth resolutions of a few nanometers can be retained to depths of several microns. The depth resolution of the deltas has been measured as a function of bevel magnification and a theory has been developed to explain the results. A peak width (resolution) of 2.2 nm for an aluminium delta has been achieved at a bevel magnification of 6000 using a 15 keV 16O2+ ion beam, and a depth resolution limit of 1.3 nm has been deduced by extrapolation to infinite bevel magnification. The combined effects of beam-induced mixing, microtopography and the escape depth of the secondary ions is a broadening of 2.0 nm for these conditions.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740231004
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  • 6
    Electronic Resource
    Electronic Resource
    A SIMS calibration exercise using multi-element (Cr, Fe and Zn) implanted GaAs (1987)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 10 (1987), S. 338-342 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Multi-element (52Cr, 56Fe and 66Zn) implanted GaAs samples have been prepared specially for SIMS calibration. Absolute chemical measurements gave retained ion doses which agreed to within 12% of the nominal implanted dose (2.0 × 1014 atoms cm-2). Comparative SIMS depth profiles with five instruments gave Cr mode depth data which showed a variability of 5%. After data normalization to a common mode depth (168 nm) the shape of all profiles showed good agreement. SIMS anàlysis of similar samples containing lower dose implants (1.0 × 1013 atoms cm-2) showed that ∼50% of the Cr was contained in the near surface region (0-0.03 μm). This surface peak was not observed in profiles of samples which had been singly implanted with Cr. It is proposed that the Cr surface peak results from radiation enhanced out-diffusion initiated by the subsequent Fe implant. Whilst the high dose multi-implant samples showed a similar Cr surface accumulation, its magnitude in relation to the ion implanted dose, was smaller. These samples therefore form reliable calibration specimens for the simultaneous determination of the secondary ion responses of Cr, Fe and Zn in GaAs.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740100705
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  • 7
    Electronic Resource
    Electronic Resource
    Quantifying the effects of uneven etching during the SIMS analysis of periodic doping structures grown by silicon MBEPaper presented at the Quantitative Surface Analysis (QSA-4) Conference, Teddington, UK, November, 1986. (1988)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 11 (1988), S. 80-87 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Problems associated with the secondary ion mass spectrometry (SIMS) depth profiling of periodic doping structures are discussed with reference to experiments on a boron-in-silicon modulation doping structure and a boron-antimony silicon super-lattice, both grown by silicon molecular beam epitaxy (MBE). The effects of uneven etching during SIMS analysis are compared with the effects of dopant diffusion during growth. Uneven etching is modelled with an algorithm in which the macrotopography of the crater base is described in terms of an unevenness function f(x, y). Simulation depth profiles involve passing craters of this topography f(x, y) through specified, laterally homogeneous, doping distributions ρp(z) in a series of equal depth interations. The predicted SIMS signal is proportional to the amount of dopant sputtered per depth iteration. The model explains the peak shapes and the loss of depth resolution with depth that are observed experimentally. The effects of dopant diffusion during growth are found by re-heating parts of the wafer to the growth temperature for various periods of time and then SIMS depth profiling them (thermal cycling).
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740110110
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  • 8
    Electronic Resource
    Electronic Resource
    Ion yield effects in the SIMS analysis of silicon delta-doped layers in GaAs (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 23 (1995), S. 723-728 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Enhancements in the secondary ion yields of Si+ and As+ ions were observed in SIMS depth profiles of Si delta-doped layers in GaAs when using oxygen primary ions. A systematic SIMS study of the enhancement in the intensity of the Si+ ion was carried out using a special test structure consisting of a series of layers with Si areal densities ranging from 0.01 monolayer (ML) to 2 ML (1 ML = 6.3 × 1014 Si cm-2). The enhancement effect was observed with layers above about 0.2 ML coverage and leads to erroneous measurements of the Si areal density for such layers. It was found that the level of the enhancement depended upon both the energy and angle of incidence of the oxygen ions. For a 2 ML delta, the level of the enhancement obtained with 5 keV O2+ ions at normal incidence was a factor of 1.2. However, using the same ion energy but changing the angle of incidence to 60° from the normal the enhancement obtained was almost a factor of 5. The enhancement was greatest when conditions for high depth resolution were used so that it was not possible simultaneously to achieve high depth resolution and accurate areal density measurements. The enhancements could not be removed by ratioing the silicon intensities to the As matrix lines (for which the enhancements are different). The enhancement effect was not observed when Xe+ or Cs+ primary ions were used and is predominantly an oxygen-induced artefact.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740231012
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  • 9
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    Thermodynamic considerations of metal halide vapour complexes (1985)
    Springer
    Details
    Publication Date: 1985-02-01
    Print ISSN: 0022-2461
    Electronic ISSN: 1573-4803
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Published by Springer
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  • 10
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    Metal halide vapour complexes: vapour transport and lamp experiments (1985)
    Springer
    Details
    Publication Date: 1985-02-01
    Print ISSN: 0022-2461
    Electronic ISSN: 1573-4803
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Published by Springer
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