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Electron Devices, IEEE Transactions on

Issue 1  Part 2 • Date Jan. 1989

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Displaying Results 1 - 25 of 39
  • Comment on progress in scandate cathodes

    Page(s): 215 - 219
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (490 KB)  

    Emission capability and emission recovery after ion bombardment are discussed. Impregnated top-layer scandate cathodes show better performance than cathodes with a mixed matrix of tungsten and scandia and impregnated cathodes with a sputtered layer consisting of tungsten and scandia. The recovery of scandate cathodes has been considerably improved, and it has been shown that fast emission recovery after ion bombardment is most probably feasible at a cathode operating temperature of 950 degrees C/sub b/.<> View full abstract»

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  • Single-crystal zirconium carbide as a high-temperature thermionic cathode material

    Page(s): 220 - 224
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    Experiments to determine the feasibility of using transition metal carbides as stable thermionic cathodes at temperatures exceeding 2000 K are discussed. The primary emphasis here is electron emission and thermal stability properties of single crystals of ZrC. To obtain accurate emission versus temperature data, the spectral emissivity at 0.65 mu m of single-crystal ZrC specimens was measured in the temperature range 1200 View full abstract»

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  • Optical performance of the silicon heterostructure switch

    Page(s): 25 - 30
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    The optical performance of a logical optical detector, that has been developed from a thin-oxide MIS silicon switch, is considered in relation to its fabrication. The analysis accounts for quantum efficiency and absorption depth. Predicted and measured results, taking these into account, show a very good correspondence. Applications include bistable switching sensors, pyroelectric detection, and robotic control systems. Since only standard processing is required, the construction of the device can be directed toward a wide range of requirements View full abstract»

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  • High transition temperature superconducting infrared detector

    Page(s): 62 - 65
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    A Y2Ba2Cu3Ox (x=6.9) bulk ceramic superconductor infrared detector operated at 77 K is discussed. The material is prepared by hot-pressing YBa2Cu 3Ox powder that was made by solid-state reaction of Ba(NO3)2, Y2O3 and CuO. The response of the detector to the blackbody radiation as a function of bias current is given for two different detector geometries View full abstract»

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  • Parameter extraction for bipolar transistors

    Page(s): 88 - 95
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (672 KB)  

    Novel methods for parameter extraction for bipolar transistors are presented. Emphasis is placed on reliable measurements of small-size transistors, examples are shown for Si integrated circuit transistors with emitters smaller than 10 μm2. Advantages over measurements on large-area test devices are discussed. Parameters measured are the current-dependent base and emitter series resistances, emitter contact resistance, base-emitter and base-collector space-charge region capacitances, junction temperature, and base and collector saturation currents. Applications to heterojunction bipolar transistors are demonstrated View full abstract»

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  • Accurate profile simulation parameters in BF2 implants in pre-amorphized silicon

    Page(s): 149 - 152
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    For the formation of shallow p+-n source-drain junctions for submicrometer CMOS technologies without the undesired channeling effects associated with B+ or BF2+ ion implantation, the surface region of the silicon wafer is preamorphized by a silicon or germanium implant. The parameters that allow accurate simulation of as-implanted boron profiles in the preamorphized silicon obtained by BF2+ implants are given. Parameters which allow simulation using either a Gaussian distribution function or a Pearson distribution function, the latter giving a slight improvement in accuracy, are provided. The energy range covered by these parameters is 15-80 keV, which results in as-implanted junction depths of 800-1800 Å View full abstract»

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  • A novel bipolar imaging device with self-noise-reduction capability

    Page(s): 31 - 38
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    A bipolar image sensor with charge amplification and noise-reduction capabilities in each unit cell is discussed. The dynamic range of linearity in the photoelectric conversion characteristics has been greatly extended by using capacitor-loaded emitter-follower circuitry and a readout operation in a deep forward-base-emitter-biasing condition. The fixed pattern noise and the random noise are reduced by introducing a hybrid reset operation that is a combination of the clamp reset and the transient reset View full abstract»

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  • Design and fabrication of 0.25-μm MESFETs with parallel and π-gate structures

    Page(s): 142 - 145
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    The design and fabrication of 0.25-μm MESFETs with a channel length of 2.3 μm is reported. A comparison of the effect of the FET geometry (π and parallel gate structures) on device performance is described. MESFETs were fabricated using a hybrid optical/e-beam lithography process on active layers grown by MBE. FETs show a transconductance of 260 mS/mm and a threshold voltage of -3.0 V. No short-channel effects were observed. From RF measurements, an f max of 90-120 GHz was obtained. Excellent device yield across a 3-in wafer and wafer to wafer was achieved View full abstract»

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  • A low-noise Bi-CMOS linear image sensor with auto-focusing function

    Page(s): 39 - 45
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    A bipolar imaging device consisting of a capacitor-loaded emitter follower circuit for a phototransistor has been implemented in a linear image sensor with two lines of 48-bit array for an autofocus camera system. The sensor, which has self-noise reduction and charge amplification capabilities, has demonstrated excellent performance, such as responsivity of 24 V/x-s, a wide dynamic range of 85.3 dB at a storage time of 10 ms and ambient temperature of 25°C, a high S /N ratio of 27.6 dB at a faceplate light intensity of 1×10-3 lx, a storage time of 200 ms, an ambient temperature of 25°C, and applicability in a range of light intensity from 1×10-3 to 1×104 lx View full abstract»

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  • Synchrotron radiation studies for thermionic cathode research

    Page(s): 194 - 200
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    An approach to thermionic cathode research is described that combines surface-extended X-ray absorption fine structure (SEXAFS) and ultraviolet photoemission spectroscopy (UPS) measurements with theoretical calculations based on the full-potential linearized augmented plane wave (FLAPW) method. The physics and chemistry of the Ba and O layer present on the surface of a dispenser cathode and the relation of its properties to cathode performance are of interest. SEXAFS determines the surface geometry associated with the overlayer and UPS the electronic properties of the Ba-O covered surface. Through the correlation of the surface geometry with the surface electronic properties via FLAPW calculations, some of the essential issues that underline the performance of dispenser cathodes are identified. Some results obtained during the initial stage of this research are presented. In particular, the results indicate that the standing-up (or vertical) geometry is unlikely for Ba-O adsorption on tungsten surfaces View full abstract»

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  • 1/2-in 768(H)×492(V) pixel CCD image sensor

    Page(s): 46 - 53
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    A sensor with unit cell dimensions as small as 8.4(H)×9.8(V) μ has been developed. In order to realize such a high-density device, the following technologies have been developed: (1) dual-channel horizontal CCD registers, (2) single p-well vertical overflow drain, (3) high-capacitance p-well structure, and (4) inverted-LOCOS channel isolation process. A horizontal resolution of more than 500 TV lines has been obtained. Maximum signal charge for the vertical CCD register is as much as 1.5×105 electrons, corresponding to 270-nA output current, in spite of a narrow-channel vertical CCD register with a mask width of only 1.8 μm. The total random noise is less than 20 electrons after correlated double sampling. The dynamic range reaches 77 dB, and the photosensitivity is 0.092 μA/μW. Experimental results also show that the technologies used here are effective for realizing a high-definition CCD image sensor for future use View full abstract»

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  • Base spreading resistance of polysilicon self-aligned bipolar transistors

    Page(s): 147 - 149
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    The base spreading resistance and its variation with current are analyzed for bipolar transistor structures in which the extrinsic base contact region extends completely around the emitter region. An analytic expression for the resistance is derived that represents the limiting case of a small rectangular emitter structure with corner-rounding. Results of the analysis show good agreement with numerical simulation results. This approach has application in the modeling of modern small-geometry bipolar transistors View full abstract»

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  • Field-emitter arrays to vacuum fluorescent display

    Page(s): 225 - 228
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    A thin vacuum-fluorescent display utilizing a matrix-addressable array of groups of Spindt-type field-emission emitter tips is described. Development of the display required expanding the cathode fabrication technology to cover 5-in-diameter areas uniformly with field-emitter arrays. Each color element of the display is addressed by a group of a few hundred emitter tips operating in parallel. Electrons emitted from the tips are proximity-focused on each color element. Because each pixel is essentially a miniature cathode-ray tube (CRT), the device has the potential to produce brightness similar to those on a CRT in a panel that is 3.3 in square (8.4 cm) in area and 0.15 in (4 mm) thick View full abstract»

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  • Organic-on-inorganic semiconductor photodetector

    Page(s): 66 - 69
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    High-efficiency high-bandwidth organic-on-inorganic (OI) semiconductor heterojunction photodetectors are discussed. The devices consist of a thin layer of the organic semiconductor perylenetetracarboxylic dianhydride (PTCDA) in contact with an inorganic semiconductor (Si) substrate. Indium tin oxide (ITO) is used as a transparent ohmic contact to the organic film. The external quantum efficiency of the detector was 85%, giving an internal quantum efficiency approaching 100%. The response time to fast optical pulses was 5 ns. Response times of OI detectors can be further reduced to about 100 ps by optimization of device parameters View full abstract»

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  • Investigation of scandate cathodes: emission, fabrication, and activation processes

    Page(s): 209 - 214
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    Top-layer cathodes have been shown to exhibit work function values in the 1.5-eV range near 1100 K. Emission from cathodes made by sputter deposition of a Sc2O3/W layer on top of an impregnated cathode were limited by the deposition conditions that cause dissociation of Sc2O3 and/or formation of volatile oxides of W. Pure Sc2O3 layers were also activated by an external Ba source to the value of the work function reported above. These results and activation mechanisms and characteristics that are peculiar to the Ba-O-Sc surface are discussed View full abstract»

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  • Intrinsic transconductance extraction for deep-submicrometer MOSFETs

    Page(s): 140 - 142
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    Significant error in the extracted intrinsic transconductance gmi can arise from source-drain resistance asymmetry. A simple procedure to either correct for or avoid this source of error is outlined. Using deep-submicrometer devices, experimental results that demonstrate the severity of the potential error and to verify the applicability of the proposed technique are presented. A method which extracts the individual values of the source and drain resistances is also described View full abstract»

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  • Cathode analysis using Raman spectroscopy

    Page(s): 188 - 193
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    Two optical detection systems used to obtain Raman spectra from impregnant samples and cathode surfaces are discussed. The advantages of each system are described and their use for cathode diagnostics is explored. The Raman spectra from various impregnant samples are given and preliminary data from cathodes at 10-9 torr and at temperatures as high as 860°C are presented View full abstract»

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  • Leakage-current reduction in thin Ta2O5 films for high-density VLSI memories

    Page(s): 14 - 18
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    Key techniques for applying Ta2O5 film to megabit-class MOS DRAMs are presented. A high-purity (4N and up) Ta sputtering target is developed to obtain high-purity Ta2 O5 film. The leakage current in Ta2O5 film that is deposited using a clean sputtering system with this high-purity target is far lower than that of film deposited with a conventional target. A previous drawback of Ta2O5, the decrease of effective dielectric constant as thickness decreases, is solved by using Mo as an electrode material. The leakage current increase that results from using metal as a bottom electrode is suppressed by reducing the electrode asperity. MOS DRAMs of up to 16-Mb capacity can be attained without trench technology by using these techniques View full abstract»

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  • High-speed sequential readout for infrared CID arrays with DC-coupled injection

    Page(s): 70 - 74
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    A high-speed readout scheme for the single-gate charge injection device (CID) linear array using DC-coupled injection (DCI) is described. In contrast to the conventional readout techniques with AC-coupled injection (ACI), DCI provides better time management in reading out the signal charge. Lower device lag is achieved by the longer injection time facilitated by DCI for a given elemental readout cycle View full abstract»

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  • Pitfalls in the evaluation of cathode properties from I V characteristics

    Page(s): 201 - 208
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    It is shown that three-halves power dependence between current and applied voltage does not guarantee sufficient electron emission all over the entire cathode area, but deviations from this dependence do not necessarily imply poor emission. The derivation of the work function from a measured I-V characteristic is obscured not only by space-charge and patch size distribution, but also by the beamlet effect. However, this effect is used to determine the barium diffusion length over a surface from a measurement of electrical current. It is also found that to obtain planar diode conditions, the distance between cathode and anode has to be smaller than about one tenth of the cathode diameter. A method that can be used to demonstrate changes in cathode series resistance curing cathode life is considered. For patchy cathodes the zero field current density is not equal to the current density obtained from Schottky extrapolation. To determine the latter properly from feasible experiments, the space charge in the saturation region has to be taken into account, i.e. space-charge correction is essential to the determination of Richardson constant and work function from a Richardson plot View full abstract»

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  • Modeling of an inversion base bipolar transistor

    Page(s): 1037 - 89002
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    Several two-dimensional numerical simulations performed to study the operational characteristics of a GaAs inversion base bipolar transistor (IBT) are discussed. The simulations show that at low base voltages the IBT operates like a junction field-effect transistor, which is characterized by a large depletion region near the base contact. At high base bias levels, there is a significant amount of hole injection into the active channel region, and the device begins to operate in the bipolar mode. The highest computed fT is 21 GHz at a collector current density of 1.3×104 A/cm2 View full abstract»

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  • A study of hydrogen passivation of grain boundaries in polysilicon thin-film transistors

    Page(s): 101 - 107
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    A series of different annealing temperatures and gases leads to steadily improving performance, i.e. lower leakage current, for five wafers containing both n-channel and p-channel transistors. Initially the n-channel and p-channel leakage currents improve proportionally for the same passivation treatment. For the best wafer, however, the p-channel leakage current improves by a factor of forty more than the n-channel leakage current. Measurement of leakage current activation energy shows that for most wafers, the activation energy is close to one half the silicon bandgap, but for the optimum wafer the activation energy for p-channel leakage current is higher by 0.1 eV. An interpretation is given in terms of the density of defect states in polysilicon. Initially passivation reduces the number of defect states near midgap, but for the optimum passivation the grain-boundary Fermi level shifts by 0.1 eV toward the conduction band, leading to a much lower leakage current for p-channel versus n-channel transistors View full abstract»

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  • RAPS-a rapid thermal processor simulation program

    Page(s): 19 - 24
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    Rapid thermal processors using incoherent light illumination have become an important semiconductor processing tool for implantation anneal, oxidation, and alloying. The application in ohmic contact alloying, however, has to be made very cautiously, for the thin metal layer drastically changes the optical characteristics and thus the thermal response of the contact region. A rapid thermal processor simulation (RAPS) program has been developed to study the difference in temperature response during rapid thermal annealing for various substrate materials and the effect of thin metal coating the substrates with films. The results are correlated with experimental observations. The results suggest that users of commercial rapid thermal processors should be cautious about the temperature-sensor setup, the application area, and the interpretation of the measured temperature View full abstract»

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  • Electronic structure of BaO/W cathode surfaces

    Page(s): 180 - 187
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    The local electronic structure of the emissive layer of barium dispenser thermionic cathodes is investigated theoretically using the relativistic scattered-wave approach. The interaction of Ba and O with W, Os, and W-Os alloy surfaces is studied with atomic clusters modeling different absorption environments representative of B- and M-type cathodes. Barium is found to be strongly oxidized, while oxygen and the metal substrate are in a reduced chemical state. The presence of oxygen enhances the surface dipole and Ba binding energy relative to Ba on W. Model results for W-Os alloy substrates show only relatively small changes in Ba and O for identical geometries, but very large charge redistributions inside the substrate, which are attributed to the electronegativity difference between Os and W. If Os is present in the surface layer, the charge transfer from Ba to the substrate and the Ba binding energy increase relative to W. Explanations are offered for the improved electron emission from alloy surfaces and the different emission enhancement for different alloy substrates View full abstract»

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  • Luminescence response of SrS:CeF3 ACTFEL devices to various pulse waveforms

    Page(s): 54 - 61
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    The steady-state luminescence responses of SrS:CeF3 ACTFEL devices to voltage plus trains of simple pulse, stepped-pulse, and notched-pulse waveforms are presented. The results are interpreted in terms of a model that ascribes the leading-edge luminescence peak to impact excitation or ionization of the activators and the downstep luminescence peak to the release of electrons from the shallower interface states, followed by trapping in the bulk phosphor and subsequent transfer to an activator-trap complex where luminescence is produced by radiative recombination. The steady-state current and luminescence response of the device to a trapezoidal waveform are in accord with the predictions of the model View full abstract»

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IEEE Transactions on Electron Devices publishes original and significant contributions relating to the theory, modeling, design, performance and reliability of electron and ion integrated circuit devices and interconnects.

 

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Editor-in-Chief
John D. Cressler
School of Electrical and Computer Engineering
Georgia Institute of Technology