Showing papers on "Field effect published in 1974"

A new ferroelectric memory device, metal-ferroelectric-semiconductor transistor

Abstract: The ferroelectric field effect has successfully been demonstrated on a bulk semiconductor (silicon) using a thin ferroelectric film of bismuth titanate (Bi 4 Ti 3 O 12 ) deposited onto it by RF sputtering. A new memory device, the metal-ferroelectric-semiconductor transistor (MFST); has been fabricated. This device utilizes the remanent polarization of a ferroeletric thin film to control the surface conductivity of a bulk semiconductor substrate and perform a memory function. The capacitance-voltage characteristics of the metal-ferroelectric-semiconductor structure were employed to study the memory behavior. The details of the study together with a preliminary results on the MFST are presented.

Frequency‐addressed liquid crystal field effect

Abstract: A new nematic material in which e∥ exhibits a dielectric loss in the audio‐frequency range is reported. At 25 °C Δ e=(e∥−e⊥) reverses sign at 2.5 kHz and can be as positive as 6.2 at low frequencies and as negative as −2.2 at high frequencies; the activation energy for the loss is 0.91 eV. The availability of a dielectric anisotropy of either sign depending on the frequency of the applied field allows the electrical orientation of the material with its optic axis either parallel or perpendicular to the electrodes. The possibilities for improving the voltage threshold and dynamic response of electro‐optical effects by means of a two‐frequency addressing scheme are demonstrated.

A simplified self-consistent model for image force and interface charge in Schottky barriers

Abstract: Some qualitative features are shown for an electrostatically self-consistent solution, initially without correlation and exchange forces, for the effect of electrons which tunnel from the metal of a Schottky barrier into the energy band gap of the semiconductor. The effect of an incremental electric field in the bulk semiconductor is deduced from a simple analytical treatment. In covalent semiconductors most of the incremental electric field terminates in the semiconductor in a manner almost independent of the nature of the metal, i.e., the effective “metal” electrode exists inside the bulk semiconductor. This is not true for ionic semiconductors. When the “metal” electrode location is used as the origin for the image force, a normal square root of the field dependence of the Schottky image force lowering is predicted at low electric fields and a linear dependence is predicted at high electric fields, both as reported recently by Andrews. The model also predicts the order of magnitude of the very small ba...

Process for fabricating insulated gate field effect transistor structure

Abstract: An improved and simplified process for fabricating a complementary insulated gate field effect transistor structure having complementary p-channel and n-channel devices in the same semiconductor substrate wherein the source/drain regions of at least one of the complementary p-channel or n-channel field effect devices are formed by the steps of introducing an impurity of one conductivity type and then introducing an impurity of the opposite conductivity type, one of the impurities having a relatively greater concentration than the other so that the one impurity counterdopes the other and the source/drain regions are characterized by the conductivity type of the one impurity.

Radiation induced electrical current and voltage in dielectric structures

Abstract: : A computational technique has been developed in one dimension for prediction of radiation-induced electrical currents and electrostatic fields in metal-dielectric slab structures High energy radiation transport effects produce divergent electron currents, time-dependent electrostatic fields, and time-dependent conduction electron currents These effects are considered and the computational technique predicts electric fields approaching breakdown intensity and time-dependent electrode currents which may even change sign Brief comments on application of the technique to field effect electronic devices are included Results are given for several metal-dielectric slab combinations under 200 keV and 125 MeV photon irradiations

Transport and localized levels in amorphous binary chalcogenides

Abstract: Measurements of photoconductivity versus intensity and temperature, photoconductivity decay, thermoelectric power versus temperature, and field effect have been extended to several binary amorphous semiconductors: Sb2Te3, As2Te3, As2Se3, and Ge2Te7, to be compared with earlier measurements on As2SeTe2 and Ge3Se2Te4 and more complex multicomponent chalcogenides. Analogous behavior is found in all these materials: about 1019 cm−3 eV−1 localized recombination levels within about 0.1 eV of the gap edges; about 1019 cm−3 eV−1 localized levels near the equilibrium Fermi level; thermally activated mobility with activation energy of the order of 0.1–0.2 eV. Crystallization produces an increase in photoconductivity at 100°K by over a factor of 106.

Field‐effect conductance change in amorphous silicon

Abstract: The change in conductance of an amorphous silicon film due to a transverse electric field was observed. The films were electron‐beam vacuum deposited at controlled rates of less than 5 A/sec onto Si–SiO2 substrates and then annealed for 4 h at 400 °C. The results indicate that the Fermi level is not pinned at near midgap and that the localized states are nearly uniform over a 0.4‐eV section above and 0.4 eV below the Fermi level near the middle of the energy gap. Calculations show the density of localized states to be 1020/eV cm3 over this region and to be reduced as the deposition rate decreases.

Electrical Properties of Gallium Arsenide-Insulator Interface

Abstract: Gallium arsenide-insulator interface properties were investigated from an analysis of conventional characteristics of MIS structures. Energy distributions of interface state density were U shape having minimum values near the mid-gap energy. The values of minimum density were dependent upon conduction types of substrates and deposition conditions of insulator films but independent of crystal orientations. They were from 0.9 to 20×1011 cm-2 eV-1 for p-type substrate and from 1 to 4×1012 cm-2 eV-1 for n-type substrate. An anomalous frequency dispersion of capacitance was observed in the accumulation region on n-type substrate and was explained by deep traps formed by oxygen atoms doped during oxide film deposition.N-channel GaAs-MISFET's were fabricated and the maximum field effect mobility of electron in the inversion layer was 1480 cm2 V-1 sec-1.

The InSb on a piezoelectric Rayleigh wave amplifier

Abstract: Results taken from monolithic acoustic surface-wave amplifiers which employ the interaction between carriers drifting in a semiconductor film and electric fields accompanying a Rayleigh wave propagating on a piezoelectric substrate are described. The experimental devices were fabricated in vacuum by flash evaporation of a InSb compound onto heated substrates of LiNbO 3 or Bi 12 GeO 20 . Theoretical and experimental amplifier results are presented for several different pulsed operating monolithic devices. The results include measurements of electronic and terminal gain, saturation power, and noise figure as a function of bias voltage, and gain and phase dispersion as a function of frequency. Results are also given for a two film device which uses field effect to alter the conductivity of the amplifier film. Results from continuously operating samples fabricated by etching the semiconductor to a strip 25 µm in width are summarized.

Driver circuit for high speed gating of a field effect transistor

Abstract: A driver circuit for gating either insulated gate field effect or junction type field effect transistors is disclosed. The circuit utilizes separate circuit paths to rapidly switch a driven field effect transistor into conducting, ON, and nonconducting, OFF, states, and exhibits a high output impedance during the ON state of the driven transistor to protect the driven transistor from excess gate current and a low output impedance during the OFF state of the driven transistor to provide maximum noise immunity.

Peaked structure appearing in the field effect mobility of silicon MOS devices at liquid helium temperatures

Abstract: Structure consisting of many weak peaks separated by approximately 0.2 V appears in the field effect mobility as a function of gate voltage of silicon MOS devices below 4K and grows with decreasing temperature. The structure is thought to be related to the sharpness of the Fermi level and to arise from the fluctuations in the density of states within the inversion layer.

A critique of a recent thin‐film field‐effect experiment using detached electrodes

Abstract: As a result of a study of the dc electric field effect on vapor‐deposited metal films using electrodes detached from the substrate, Murr and Singh recently observed no significant effects for fields applied in the plane of the substrate, ranging from 10 to 103 V/cm. It is demonstrated in the present paper that a linear gradient did not exist during these experiments, and that due to a counteracting influence of the displacement current, the potential gradient at the substrate surface probably approached zero almost instantaneously at elevated substrate temperatures. An analysis of the field conditions attendant to thin‐film field‐effect experiments with detached electrodes indicates that the effect of dc electric fields on nucleation and growth of vapor‐deposited thin films in such an experiment can only be established when the substrate temperature is relatively low.

Field effect in small filaments of chalcogenide glasses

Abstract: A field effect has been measured in a semiconducting chalcogenide glass, of composition Te2AsSi. The sample was in the form of a fine filament, encapsulated within a rod of insulating glass, with the bias field applied radially. The effect is small, and the change in conductivity increases more slowly with field at high fields than at low fields. The results are explained in terms of a model with a uniform density of bulk states near the Fermi energy and a sharp surface level just below the Fermi energy. There is a depletion layer at the surface at zero bias, hence the surface barrier with no external field varied with each sample.

Electron and neutron damage in n− and p−Channel junction field effect transistors

Abstract: The electrical properties of Si n− and p−channel junction field effect transistors (JFET's) were measured after irradiation with fast neutrons and 1 MeV electrons, before and after annealing up to 675 K. A pulse technique was used to measure the energy levels of the radiation defects. It was found that one of the defects in the n−channel JFET's had an energy level at approximately EC −0.4 eV and, in the case of electron damage, annealed sharply at about 425 K. These properties suggest that the defect is the Si‐E centre. The energy level of the major source of damage in the p−channel JFET's could not be measured by the techniques used but the annealing temperature of 600–675 K agreed with that of the Si‐K centre. Considerable recovery in properties of the neutron damaged p−channel devices can be achieved by forward biasing the gate at room temperature.

Mobility-dependent field-effect conduction of vacuum-deposited CdSe layers.

Abstract: Temperature- and photo-effects of CdSe thin-film transistors are analyzed experimentally on their mutual characteristics, comparing with results obtained from the related Hall-effect measurement. The analysis manifests a fact that the change in the mobility by applied gate voltage plays a principal role in the field-effect conduction of vacuum-deposited CdSe layers.

Metal Oxide Semiconductor (MOS) Field-Effect Transistors

Abstract: The use of the field effect for constructing practical transistors may follow several different principles. In figure 2.1 a cross-section of a rectangular piece of semiconductor with ohmic contacts at both ends and an insulated gate electrode on top is shown. A voltage applied on the gate induces charges in the semiconductor and thereby changes the resistance between the contacts. If the semiconductor is doped, there are initially so many free charge carriers that the additional induced charges are hardly noticeable. Such a device has very low sensitivity.

Effect of Surface Charge on the Superconductivity of Vanadium Films

Abstract: Electrostatic charging affords a direct method of changing the number of electrons at the surface of a metal film The sample serves as one plate of a capacitor across Which a voltage is applied. Charging occurring at the surface of a superconducting film with thickness smaller than the coherence length can be expected to affect the superconducting transition temperature of the entire sample. This “superconducting field effect” has previously been investigated for a considerable number of metals (see, e.g., Ref. 1).

The Influence of Landau Level Broadening on the Shubnikov-De Haas Effect in Two-Dimensional Conductors

Abstract: The density of states at the Fermi energy for two-dimensional conductors in a perpendicular magnetic field is calculated for Lorentzian broadening of the Landau levels. The results are compared to published experimental data on the magnetoresistance of field effect devices.