Showing papers on "Field effect published in 1984"

Potential disorder in granular metal systems: the field effect in discontinuous metal films

Abstract: The authors show that the conventional model for the basic physics of conduction in granular metals is unable to account for low-temperature field-effect measurements on discontinuous metal films. They discuss the physics of electrical contact between metals and insulators and show that it results in potential disorder that is large in comparison with other relevant energies. They explore the idea of electrostatic relaxation in the insulator and show that it correctly accounts for the small field effect that is observed and for its dependence on temperature and the activation energy for conduction. They have verified the role of electrostatic relaxation by direct experiments in which the relaxation processes are modified with the predicted consequences. They assert that potential disorder must play a dominant role as regards electrical transport in all granular systems.

Polysilicon Super-Thin-Film Transistor (SFT)

Abstract: N-channel MOS FET's have been fabricated in super-thin polysilicon film on quartz substrate. The thickness of the film had an important role in improving the electrical properties. Moreover, grain boundary passivation by the hydrogen from a plasma-SiN film has been developed to increase the field effect mobility. The field effect mobility is more than 20 cm2/Vs at the polysilicon thickness of 150–200 A; and threshold voltage and leakage current are reduced to 6 V and 10-13 A/µm, respectively. The device obtained in this work can be used not only for flat panel matrix displays but also for other applications.

GaAs level-shift logic interface circuit

Abstract: A very high speed, low power integrated interface circuit using GaAs or InP technology is provided for converting small digital voltage swings to larger swings which are particularly suitable for analog control signals. The preferred embodiments employ solely depletion mode MESFETS and Schottky diodes in Schottky diode field effect logic (SDFL) configurations.

Semiconductor devices and manufacturing methods

Abstract: A field effect device having a gate over a portion of a surface of a semiconductor disposed between a source region and a drain region and including a buried doped region having a conductivity type opposite the conductivity type of the semiconductor formed in the semiconductor under, and spaced from such portion of the surface of the semiconductor. The buried doped region is electrically connected to the gate electrode. With such arrangement a field effect device is formed with a connecting channel having a shallow depth in the semiconductor between the gate and the buried doped layer. A method for fabricating field effect devices is also disclosed, such method including the step of forming a pair of masking surfaces of insulating material on the surface of the semiconductor. An ion implantation masking layer is formed between the pair of masking surfaces to enable the selective implantation of particles in the semiconductor to establish the source and drain regions. With such method a single level of masking is used to define the source, drain and gate regions of the device.

Field emission and field ionization in a liquid metal cesium field-effect source

Abstract: Analyse des parametres d'emission d'une source a effet de champ a Cs liquide soit en mode d'emission de champ, soit en mode d'ionisation de champ, suggerant un processus d'ionisation de champ dans chacun des modes

Charge injection into SiO2 during field effect and photo‐field‐effect measurements in hydrogenated amorphous silicon

Abstract: It is shown that electron and hole trapping in vitreous quartz occurs when fields larger than 105 V/cm are applied across the insulator of glow‐discharge deposited amorphous silicon (a‐Si:H) field effect devices. The trapping of charges of both polarities is enhanced by light having energy less than 2 eV. The charge trapping reduces the field effect and the photo‐field‐effect of a‐Si:H at large gate voltages. It is found that strong illumination does not eliminate the effect of accumulation layers on the photoconductivity.

Fet charge sensor and voltage probe

Abstract: A MOSFET structure having a biased gate covered with an insulator of such a thickness as to render the structure capable of giving a measure of accumulated charge and usable in a stacked structure as a particle spectrometer.

Noise characteristics of a cryogenically cooled GaAs metal semiconductor field effect transistor at 4 MHz

Abstract: The noise near 4 MHz of a cryogenically cooled GaAs metal semiconductor field effect transitor (MESFET) has been measured. The input noise current is iN=1.1±0.2×10−14 A/(Hz)1/2 and the additive voltage noise is eN=1.2±0.4×10−9 V/(Hz)1/2 , which gives a noise temperature TN=0.5 K.

A.C. field effect study on PbTe films grown by hot wall epitaxy technique

Abstract: The field effect mobility on the free surface of PbTe films grown by hot wall epitaxy (HWE) technique ona KCl substrate was studied as a function of frequency in the range 40–200 kHz at different temperatures from 98–156 K. Using Garrett's theory of the frequency dependence of field-effect mobility, the relaxation times of surface states were found to vary from 1.84 to 0.96 μsec in the above temperature range. From Rupprecht's relation on temperature dependence of relaxation times, the energy level of surface states was found to be 0.02 eV below the conduction band with an effective capture cross section of the order 10−19 cm2.

The interface and the field effect in thin‐film transistors

Abstract: The effects of interface properties on the performance of thin‐film transistors are examined theoretically. The static characteristics, e.g., the off conductance and the on‐off ratio, and the dynamic response represented by the fraction of induced charge that is free, are considered. The interfaces, both at the gate side and the substrate side, are specified by the interface charge transfer (at equilibrium) from the semiconductor to the insulator, as well as the more familiar density of interface states. The properties of the two interfaces are found to control different regimes (high field and low field) of field‐effect conductance. Thus, by a careful tailoring of the two interfaces, and/or the two insulator materials, the transistor characteristics can be optimized.

Insulated gate field effect type semiconductor device

Abstract: PURPOSE:To enable to reduce a resistance component inserted to a protection diode in series by a method wherein a reverse conductivity type diffused layer conneting a wiring to an external lead-out electrode and an electrode connected to one conductivity type substrate, through a field oxide film on the surface of the semiconductor in the neighborhood of the diffused layer, and supplying a substrate potential are provided on the one conductivity type semiconductor substrate. CONSTITUTION:The poly Si wiring 10 which is provided, via an insulation gate oxide film, on the source and drain region 12 of an N-channel Si gate MOSFET, and constitutes a gate electrode 11 is connected to an input terminal 13 by means of an N type diffused layer 14. In the neighborhood of this N type diffused layer 14, an aluminum potential wiring for a substrate potential 18 which penetrates through a field oxide film 16 and becomes in ohmic contact with a P type high concentration layer 17 formed on the surface of the P type semiconductor substrate 15 is formed. In an MOS semiconductor device formed in such a manner, when impressed by an overcurrent 13, the current flowing through a protection diode formed of the N type diffused layer 14 and the P type semiconductor substrate 15 flows from the surface of the substrate 15 to the electrode wiring 18 as shown by an arrow mark 19.

Field effect device

Abstract: PURPOSE:To obtain a high speed FET by a method wherein an electric field is impressed, on a semi-metallic thin layer generated in the neighborhood of an interface by the combination of a semi-metallic layer of Bi, etc. or a suitable semiconductor film, via a hetero junction of an insulation film or a semiconductor, and thus controlling the semi-metallic layer. CONSTITUTION:The Bi 12 approx. 80nm thick is adhered on an N type Si substrate 11 of 0.1OMEGAcm. The layer 12 is a semi-metallic layer which has electrons and holes at 2X10 cm and has a large value of approx. 8X10 cm /V second in electron mobility at an extremely low temperature (4.2 deg.K). An Al2O3 13 of 50nm is superposed on the Bi 12, and a gate, a source, and a drain electrode 14-16 are laid by Au of 1,000nm. The concentration of electrons and holes in the film 12 is changed by impressing an electric field on the Bi film 12 in the direction of width. The conductivity at an extremely low temperature is decided only by the electrons, the conductance varies rapidly, and then the FET of superhigh speed actions can be obtained. The thin layer of semi-metallic properties can be obtained also at the interface of InAg-GaSb, and accordingly the FET of likewise high speed actions can be formed.

On the field-effect in amorphous tetrahedral photoreceptors

Abstract: The imaging properties of photoreceptor structures based on amorphous silicon are discussed. When the external surface of such structure is an electrically insulating film, it functions during the imaging process like the gate insulator in a thin film transistor. The resulting field effect phenomena are shown to decrease the attainable electrophotographic resolution. Methods are discussed to counteract the occurence of the field effect in photoreceptors made of tetrahedrally bonded amorphous materials.

Field‐effect studies on p‐type CuInTe2 metal‐insulator‐semiconductor structures

Abstract: Field effect studies on metal‐insulator‐semiconductor structures of p‐CuInTe2 thin films grown on mica are made in the temperature range 77–295 K. An increase in carrier density and a decrease in the mobility is observed on the application of a negative gate field. The effect of a positive gate field is the opposite. The Hall coefficient is found to remain practically constant at a lower temperature range (77–180 K) and then decreases with a further rise of temperature. The study of the effective field effect mobility μFE reveals that the surface states charge scattering mechanism dominates the scattering process.

Properties of Injected Charge Carriers at Intermittent and Permanent Polystyrene/Metal Interfaces

Abstract: The electric and electrostatic properties of polymers with negligible intrinsic charge carrier concentration are determined by the ratio of injection of excess charge carriers, e.g. from a metal electrode, to the rate of charge transport. Both, injection and transport of charge carriers are affected by polymer specific interface parameters, e.g. energy level of the polymer band gap states, barrier heights between these levels, band bending situations, orientation and dipole relaxation in the bulk near the surface, as well as experimental parameters like work function of the contacting metal, contact ratio and contact frequency. The resulting space charge and dipole orientation distribution near polymer metal interfaces, which is concentrated within a region smaller than 1 ?m near the polymer surface, is measured experimentally and calculated by simple model assumptions. Experimental results of two different experimental techniques which are intermittent contact electrification and electrical field effect are compared and commonly discussed under these viewpoints.

Field effect type liquid-crystal display element

Abstract: PURPOSE:To prevent orientation inversion during electric field application and eliminate the need for special electric signal processing by devising an electrode shape. CONSTITUTION:A crossing pattern of a common electrode 3 and segment electrodes 4' is formed. Cut parts 7 are formed in the electrodes 4' to reduce the influence of lines of electric force at edge parts of a dotted pattern, preventing the orientation inversion during the electric field application of liquid crystal molecules. When dimensions (a), (b), (c), and (d) are about 30, 120, 300, and 350mum, excellent display quality is obtained. The cut parts 7 are only provided where the orientation inversion of liquid crystal occurs at end parts of intersections of the electrode 3 and 4'. Therefore, the cut parts 7 are different in arrangement position when the direction of a normal visual angle area is different.

Optical recording using field-effect control of heating

Abstract: To form an optical image, an imagewise pattern of conductivity is formed in a semiconductor material. Exposing the material to an intense radio-frequency field causes generation of heat in the conductive areas. The semiconductor is made of a heat-sensitive material or includes a heat-sensitive material. The heat-sensitive material responds to heat by physical changes which can be optically detected. Preferably the semiconductor is a photoconductor with surface charge capability retention which allows formation of a conductivity pattern by normal xerographic processes.

ON THE NONLINEAR FIELD-EFFECT OF ORTHORHOM-BIC TaS 3

Abstract: The true dc measurement of electrical field effect on the resistivity of orthorhombic TaS 3 in the CDW state was performed for the first time with extremely short distances between the contacting leads. Very weak nonlinear effect was observed up to 1300 V/cm. A distinct resistivity-increasing effect was found, which can not be understood within the framework of any currently available theories. We propose a transverse tunneling model to account for this anomaly.

Metallic oxide semiconductor field effect type semiconductor device

Abstract: PURPOSE:To improve the write efficiency of an FPROM and contrive to increase the withstand voltage by a method wherein a semiconductor layer of a low impurity concentration and that of a high one are provided on the same semiconductor substrate, and a memory transistor is formed at the region of a high impurity concentration, and the other transistor at the region of a low one. CONSTITUTION:A semiconductor single crystal growth layer 24 of a low impurity concentration of the same conductivity type is formed on the semiconductor substrate 23 of a high impurity concentration of one conductivity type, and, in the grown layer 24, the region 25 of the same conductivity type and higher impurity concentration than that of said layer 24 which reaches from the main surface of said layer 24 to the substrate 33 is formed. The EPROM memory transistor 21 is formed in the region 25, and the peripheral circuit transistor 22 is formed in the grown layer 24. Therefore, the write efficiency is improved, and the source-drain withstand voltage can be increased by forming the memory transistor at the region of a high impurity concentration.

Field effect type semiconductor chemical sensor

Abstract: PURPOSE:To eliminate the effect affected to the potential in a measured solution by the potential of a substrate, source, drain and the like by a method wherein the surface of an FET sensor is covered with a semiconductor layer except a channel region and the semiconductor layer is biased at a suitable potential. CONSTITUTION:When an FET sensor is used as a PH sensor, the surface of its nitride film 15 is dipped in a solution 20 to be measured. An electrical double layer is produced between the surface of the nitride film. A current which flows between a source 12 and a drain 13 is modulated by a potential produced by the electrical double layer and this modulated current is measured to obtain the PH value of the measured solution 20. The surface of the FET sensor is covered with a semiconductor layer 31 except a gate layer and electrical contact metals 17. A potential is given to the semiconductor layer 31 by a terminal 32. As a substrate 11, the source 12 and the drain 13 are shielded by the semiconductor layer 31, their potential has almost no effect to the potential in the measured solution. It is preferrable to make the potential of the semiconductor layer 31 and the potential of a comparing electrode 26 nearly equal with each other.

Characteristics of Amorphous Silicon Based Alloy Field Effect Transistors

Abstract: We have developed a new theory to describe the current-voltage characteristics of amorphous silicon based alloy field effect transistors. We show that the transition from below to above threshold operation occurs when the Fermi level in the accumulation region moves from the deep to tail localized states in the energy gap and that the field effect mobility is dependent on gate voltage. We also propose a new technique to determine the flat-band voltage from the I-V characteristics in the below threshold regime.

Crystal field effect in planar ferromagnets

Abstract: Correlated effective field theory which includes fluctuations semiempirically has been used here to study the crystal field effect on the magnetic behaviour in planar ferromagnets. An attempt has been made to reproduce the experimentally observed magnetic order parameter of a planar ferromagnet (Rb 2 CrCl 4 ) with a suitable choice of crystal field and exchange parameters. An alternative model Hamiltonian with anisotropic exchange and no crystal field effect has been considered to reproduce the same experimental results. Both calculations have been compared with the standard RPA results and the existing theoretical results.

Metal-Semiconductor Field Effect Transistors

Abstract: It is now over 15 years ago that the first gallium arsenide field effect transistors were fabricated. Since then major programs worldwide have enabled the device to be developed into a commercial production item opening up many new applications areas both in low-noise receivers and in transmitting circuitry.

Optical control system of amplitude for superhigh frequency active circuit

Abstract: PURPOSE:To simplify the entire circuit constitution and to decrease the power consumption by controlling directly the amplitude of a superhigh frequency electrical signal of a superhigh frequency active circuit by means of the intensity or wavelength of light CONSTITUTION:Let a field effect transistor (TR) 11 made of a photo semiconductor material, eg GaAs be a semiconductor active element constituting a superhigh frequency active circuit 4, eg, a superhigh frequency amplifier Further, when a light L is made incident to the field effect TR11, an electrical signal taking a level in response to the intensity or wavelengh of the light L is led out from the field effect TR11 and the superhigh frequency electrical signal having the amplitude controlled by the light L is obtained

Electrical Conductivity Regulated by Transverse Electric Field in the Hot Electron Range in n-Type Silicon

Abstract: An attempt was made to control the electrical conductivity of n-type silicon by utilizing the anisotropic character of hot electrons The I –V characteristics were measured in the presence of electric fields at 77 K The roles of the intervalley redistribution and the intravalley scattering of hot electrons in the observed results are discussed on the basis of an expression for the mobility in the direction