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IBM Journal of Research and Development

Issue 2 • Date March 1966

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Displaying Results 1 - 10 of 10
  • Formation of Built-in Light-emitting Junctions in Solution-grown GaP Containing Shallow Donors and Acceptors

    Page(s): 114 - 121
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (599 KB)  

    The growth of GaP from a gallium-rich solution is described and the morphology and dendritic growth habit of the crystals are discussed. By control of growth conditions it was possible to produce built-in junctions in crystals doped with the shallow donors, S, Se, or Te, and the shallow acceptor, Zn. Green junction electroluminescence of higher efficiency than has been reported heretofore was observed from these structures. The effective segregation coefficients for the above impurities in GaP were determined by radiochemical techniques. On the basis of differences existing between these coefficients for the donor and acceptor dopants, and with the assumption of a two-step growth process, a mechanism for the formation of the junctions during precipitation of the crystals from solution is set forth. View full abstract»

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  • Green Luminescence from Solution-grown Junctions in GaP Containing Shallow Donors and Acceptors

    Page(s): 122 - 129
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (552 KB)  

    Gallium phosphide diodes doped with shallow donors and acceptors that partially compensate one another in both the n- and p-regions give rise to bright green emission. This green emission is more efficient at room temperature than the so-called “A-line” emission commonly observed in lightly doped diodes. The peak energy of the green emission varies with the donor binding energy, and the emission is interpreted as a radiative donor-acceptor or a donor-valence band transition. Its intensity-voltage dependence and its current-voltage dependence are discussed for room temperature conditions. At 77°K, large shifts in peak energy were observed to accompany changes in applied voltage. Data concerning this peak shift, the intensity-voltage dependence, and the linewidth-voltage dependence are presented and discussed. Time effects and the temperature dependence of the quantum efficiency are also examined. View full abstract»

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  • Effects of a Keeper on Thin Film Magnetic Bits

    Page(s): 130 - 134
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (364 KB)  

    When Permalloy films are used for computer storage, a magnetic keeper can improve performance by reducing the following undesirable conditions: stray fields from adjacent lines and from adjacent bits; the effect of current spreading in the ground plane; and trapped flux in the ground plane which opposes switching in the absence of a low reluctance path outside the bit. Theoretical analysis and experimental verification of these important keeper functions are presented in this paper. Through the use of high-frequency pulse techniques, effects of both metallic and non-metallic keepers, at distances from the ground plane ranging from 5 to 30 mils, have been determined. By defining efficiency as the percentage reduction in the average of four worst-case effects, the efficiency factor of a metallic keeper is shown to be 56 and that of a non-metallic keeper, 73. It is suggested that better efficiency is due more to lower electrical conductivity than to any intrinsic magnetic properties. View full abstract»

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  • Pert as an Aid to Logic Design

    Page(s): 135 - 141
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (415 KB)  

    A new application is presented for pert, the well-known statistical project-scheduling method. Using PERT, the logic designer could circumvent usually unrealistic worst-case criteria. He substitutes a formalized statistical method which determines (1) expected or most probable delays, (2) critical timing paths, (3) timing slack allowable between various inputs, and (4) probability of achieving an output by a certain time. From these data the designer can make a meaningful judgment regarding the reliability of his system. Significantly, he may achieve high reliability without being forced to resort to worst-case design. View full abstract»

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  • Design of a Printed Card Capacitor Read-Only Store

    Page(s): 142 - 157
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (877 KB)  

    The Printed Card Capacitor Read-Only Store system is introduced as one of three Read-Only Store (ROS) technologies presently employed in the IBM System/360 computers. A detailed description is given of the elementary storage structure—a capacitor matrix with a novel arrangement for rapidly and economically changing the matrix configuration. The changeable element is an etched or printed Mylar card, prepared with standard IBM card-punch equipment. The assembly of storage structures into a compact 4032-word, 60-bit module is described. Considerations involved in the selection of matrix parameters are reviewed and a theoretical analysis of matrix performance is presented. It is shown that some of the limitations associated with a linear matrix are minimized by an incomplete integration of the matrix output. The impact on over-all ROS performance of factors external to the capacitor matrix is considered. These factors include the effects of a noisy drive system and the asymmetrical character of the matrix relative to the access circuitry. Computed and observed results are compared for typical System/360, Model 30 ROS operation. The actual matrix response amplitude is observed to be greater than the computed value due to the level of system background noise; however, computed and observed waveforms are otherwise in good agreement. View full abstract»

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  • A Practical Class of Polynomial Codes

    Page(s): 158 - 161
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (358 KB)  

    Error detecting polynomial codes are usually formed by defining a correspondence between data bits and coefficients of the representative polynomial. These codes are easily implemented in hardware using shift registers; however, implementation in character-oriented processors may be too time consuming. A new class of polynomial codes is described for which a correspondence between n-bit data characters and polynomial coefficients is defined. Two particular types of these “character polynomial codes” are discussed; these may be easily implemented with hardware or with processor character manipulations. The burst error detecting ability of these two types of codes is shown to be the same as for the common “bit polynomial codes." View full abstract»

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  • Stimulated Emission Observed from an Organic Dye, Chloro-aluminum Phthalocyanine

    Page(s): 162 - 163
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (279 KB)  

    We have observed that when a specific phthalocyanine solution (chloro-aluminum phthalocyanine dissolved in ethyl alcohol) is irradiated by a sufficiently powerful beam from a giant-pulse ruby laser, there occurs intense stimulated emission from the phthalocyanine molecules. The wavelength of this stimulated emission is centered at approximately 0.755 µ. Its spectral half-width was observed to be some 5 cm−1. View full abstract»

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  • Technical Papers by IBM Authors Published Recently in Other Journals

    Page(s): 164 - 180
    Save to Project icon | PDF file iconPDF (874 KB)  
    Freely Available from IEEE
  • Recent IBM Patents Assigned to IBM

    Page(s): 181 - 182
    Save to Project icon | PDF file iconPDF (239 KB)  
    Freely Available from IEEE
  • Authors

    Page(s): 183 - 184
    Save to Project icon | PDF file iconPDF (206 KB)  
    Freely Available from IEEE

Aims & Scope

The IBM Journal of Research and Development is a peer-reviewed technical journal, published bimonthly, which features the work of authors in the science, technology and engineering of information systems.

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Editor-in-Chief
Clifford A. Pickover
IBM T. J. Watson Research Center