Showing papers on "Field effect published in 1980"

Electrical and photoconductive properties of ion implanted amorphous silicon

Abstract: The results of a systematic study of ion implantation doping in glow discharge a-Si films using groupIII and V substitutional impurities and alkali interstitial ions are described. Implantation doping provides the same range of control of the electrical properties as gas phase doping, but at a lower doping efficiency. The characteristics of an implanted p-n junction, produced by compensation of pre-doped material, are shown. The effect of implantation damage on electrical properties has been investigated by photoconductivity measurements. Finally, the implantation results are used to determine an approximate density of state distribution for a-Si which is compared with field effect data.

Determination of the density of states of a-Si:H using the field effect

Abstract: We have devised a new iterative computer method for obtaining N(E), the density of gap states, from field effect data without using simplifying approximations. Our analysis shows that equally good fits to the data can be obtained over a range of values of the ratio of electron and hole contributions to the conductivity in the bulk and of the field voltage needed to obtain flat bands. We find that the present experimental accuracy is not sufficient to discern detailed structure in N(E). the validity of assuming a parallel shift of the mobility edge with the potential near the interface is being questioned. Field effect data on undoped glow-discharge a-Si:H subjected to the Staebler-Wronski cycle of illumination and heat treatment are presented and analyzed. We find N(E F ) ∼ 10 17 e V −1 cm −3 and lower N(E) below the gap center.

Enhancement mode JFET dynamic memory

Abstract: A multiplicity of field effect type semiconductor memory elements are formed perpendicular to a surface of a semiconductor wafer. Charge carriers are transported in the semiconductor bulk perpendicular to the surface and a potential barrier is formed in the current path to accomplish storing. Since the bulk mobility of a semiconductor is far larger than the surface mobility, the transit time of the carriers is much improved. Furthermore, since each structure of the memory cells is formed perpendicular to the semiconductor surface, the surface occupation area per memory cell is reduced. Thus, a high-speed and high-density semiconductor memory device is provided.

Field effect semiconductor laser, method of modulation thereof

Abstract: A field effect semiconductor laser has two clad layers and an active layer therebetween, formed by an epitaxial growth on a semiconductor substrate, which is mesa-etched to form a stripe-shaped mesa part of a double heterostructure on the semiconductor substrate. The laser further includes first and second buried layers of conductivity types opposite to each other and formed on both sides of the mesa-etched part, respectively. Gate electrodes G are formed on at least one of the top faces of the buried layers, and a drain electrode D is formed on the mesa-etched double heterostructure part. Depletion layers are produced at the junction interfaces between the first and the second buried layers when a reverse-bias voltage is applied across pairs of these buried layers. The thickness of the depletion layers, and thus a refractive index of a part of the buried layer neighboring outside the active layer, can be controlled by changing the external voltage applied to the gate electrode G, and the laser oscillation can be directly controlled by a voltage signal thereby enabling effective and high speed modulation of the laser.

Field effect measurement on the film‐substrate and film‐vacuum interfaces of a‐Si:H

Abstract: Field effect experiments on a‐Si:H films at the bottom (film‐substrate interface) and the top (film‐vacuum interface) of the film are reported Because of the presence of an absorbate at the top surface, the field effect at the top is found to be much smaller than at the bottom After a heat treatment at 175 °C for two to four hours, the field effect at the top and the bottom are found to be similar

Electrical and structural properties of cadmium selenide thin film transistors

Abstract: Stable thin film transistors based on cadmium senenide and silicon dioxide have been prepared. The degree of stability implies a decay of only 10% in drain current in 100 years of continuous d.c. operation. The decay is solely due to tunnelling of electrons into insulator traps and has a logarithmic time dependence. The devices have field effect mobilities up to 140 cm 2 . Volt −1 sec −1 , switching ratios in the range 10 5 –10 6 , and good reproducibility. The CdSe films contain the hexagonal structure and grain growth occurs during anneal. Grain size and distribution are reproducible from run to run.

Method for manufacturing a semiconductor device utilizing selective epitaxial growth and post heat treating

Abstract: Disclosed is an improved method of growing an epitaxial layer preventing auto-doping from a doped region exposed to a surface of a semiconductor substrate. A surface of a semiconductor substrate of one conductivity type is covered with a mask having a predetermined opening. Then, impurity atoms are doped into the substrate through the opening to form a region of the other conductivity type. An epitaxial layer of one conductivity type is deposited over the exposed surface of the substrate with another mask which covers the entire surface of the region and has an area larger than that of the exposed surface of the region. The latter mask prevents auto-doping from the region of the other conductivity type. The process is usable for controlling, for example, channel widths of field effect semiconductor devices uniformly and precisely.

Light-responsive field effect mode semiconductor devices

Abstract: A field effect semiconductor device comprises a P-N junction with a depletion layer responsive to radiant energy for controllably enabling the field effect semiconductor device. The depletion layer occurs near at least a pair of gate locations within a silicon substrate. The gate locations are of P-type while the silicon substrate is of N-type. The depletion layer is rendered ineffective by photoelectromotive force derived from the radiant energy. A channel emerges according to the shrinkage of the depletion layer to thereby provide electrical connection between a source and drain electrodes of the field effect transistor.

Integrated circuit and manufacturing method

Abstract: A method used to form a field effect device and a bipolar device in different regions of the same semiconductor material, such method including the step of forming a doped layer in the semiconductor material which extends from the surface of the semiconductor material to a predetermined depth in such semiconductor material and which extends laterally along the surface of the semiconductor material through the different regions wherein the field effect device and the bipolar device are formed. Such formed doped layer has the same type conductivity as that of the semiconductor material but has a doping concentration at least an order of magnitude greater than that of the semiconductor material. The doping concentration of the doped layer is sufficiently high to prevent undesired surface state inversion effects and enable effective control of the channel width of the field effect device. On the other hand, the doping concentration of the doped layer is sufficiently low to provide proper breakdown voltages for both the bipolar device and the field effect device. In this way, since the same doping concentration is used for both the bipolar device region and the field effect device region, the doped layer may be formed in the entire surface region of the semiconductor material without the requirement of additional masking steps. Further, with a buried channel field effect device the portion of the doped layer in the field effect device region provides the upper comparatively higher doped gate portion of the device while the portion of the semiconductor material below the buried channel region provides the lower gate portion of the device, such upper and lower gate portions being coupled to a gate electrode to enable control of the effective channel width from both upper and lower sides thereof.

Simplified BIFET structure

Abstract: In a monolithic semiconductor integrated circuit, conventional bipolar transistors are fabricated along with thin ion implanted junction field effect transistors, to create BIFET structures. After the conventional isolation diffusion, the surface oxide is stripped off and the semiconductor wafer ion implanted with slow diffusing impurities of a conductivity type, the same as the undiffused surface material. Then the bipolar transistors, along with the junction field effect transistors, are fabricated using conventional oxide masked diffusion processes. The field effect device sources and drains employ the base diffusions of the bipolar transistors while the gate contact is achieved with an emitter diffusion. The field effect device channels are formed at a depth substantially greater than that of the impurities deposited in the original ion implant. If desired, an ion implanted top gate can be established over the channel. The wafer is then annealed and processed in accordance with conventional techniques. Since the original ion implant covers the entire surface of the circuit, it will act as a field inversion prevention layer thus, improving the circuit reliability. The field effect devices can be fabricated with one less masking step when compared with the prior processes.

Field effect semiconductor structure

Abstract: A metal semiconductor field effect transistor (MESFET) is provided with a laminated channel (8) consisting of alternating layers (9, 10) of two semiconductors, one having a narrow energy gap and light doping and the other having a wide energy gap and heavy doping. GaAs and GaAIAs, respectively, can be used for the alternating layers (9, 10).

Field effect semiconductor device having a protective diode with reduced internal resistance

Abstract: A semiconductor device comprising a semiconductor element having an insulated gate electrode and a protective diode region provided in the neighborhood of the semiconductor element to protect the gate electrode from a dielectric breakdown; the diode is formed by a low resistivity semiconductor material to reduce its internal resistance, thereby accelerating the action of the protective diode so that the clamp action of the diode occurs earlier than the dielectric breakdown of the gate electrode.

Field effect studies in p‐type InSb MIS structures

Abstract: Field effect studies on MIS structures of silver‐glass p‐type InSb have been made in the temperature range 77–300 K. It has been observed that the effect of negative gate voltage is to decrease the Hall coefficient, Hall mobility, and grain boundary barrier potential, while the effect of positive gate voltage is opposite but less significant. The results can be explained in terms of accumulation and depletion layers, induced on the surface.

Charge-Carrier Transport in Semi-Insulating InP Surface Layers

Abstract: The surface charge-carrier transport and electronic properties of n-type, Fe-doped, -oriented, Czochralski-grown, semi-insulating InP were investigated by means of field effect controlled galvanomagnetic measurements. It is shown that the surface Fermi level is pinned 0.16 eV below the conduction band, that such surfaces are accumulated, that typical surface electron densities are of the order ns ~ 1011 cm-2 and corresponding mobilities are of the order μ s ~ 5 × 102 cm2 V-1 s-1 and that they are functions of the oxide deposition process. Optimum procedures yield ns ~ 1012 cm-2 and μ s ~ 9 × 102 cm2 V-1 s-1.

Semi-conductor inverter using complementary junction field effect transistor pair

Abstract: A semiconductor inverter comprised of a pair of junction field effect transistors A first of the junction field effect transistors is a lateral transistor, and a second of the junction field effect transistors is a vertical transistor The two junction field transistors have respective channels of opposite conductivity type

Cooperative charge disproportionation of defects in amorphous semiconductors

Abstract: Defect centers in amorphous semiconductors with three possible states of charge (+, 0, and -) can be modeled with an antiferromagnetic S = 1 Ising Hamiltonian in an external field. We have studied this model on a one-dimensional lattice with first neighbor interactions. A clear charge disproportionation is obtained as a function of temperature for a wide range of parameters. The relevance of our finding to the ESR behavior of a-As, and possibly also the photoluminescence of a-Si:H, and to field effect behavior of chalcogenide glasses is pointed out.

Field effects semiconductor devices

Abstract: In a field effect semiconductor device comprising a semi-insulator layer composed of a semiconductor material, an N conductivity type active layer made of the same semiconductor material and acting as a channel, spaced cathode and anode electrodes formed on the active layer, the cathode electrode being in ohmic contact with the active layer, and means for applying drive voltage across the cathode and anode electrodes for varying the electrons flowing through the active layer so as to vary output current, a P conductive region is provided beneath the anode electrode and extending through the active layer toward to or penetrating into the semiconductor layer.

Numerical determination of potential and flux conserving static equilibria of liquids

Abstract: Electric or magnetic fields can augment gravity and surface tension in determining the shape of liquid interfaces. In an electric field, a static equilibrium is possible if the interface conserves its potential. Water films and drops on or in the vicinity of high voltage electrodes are examples. For there to be a static equilibrium in a magnetic field, there must be no normal flux at the interface. Liquid metals subjected to high-frequency fields provide examples. Theoretical descriptions are difficult because not only does the field alter the interfacial shape, but the field distribution is in turn determined by the field dependent geometry. A numerical approach is described in which the fields are represented in terms of discretized surface sources equivalent to the surface tractions needed to represent the field effect on the mechanics. Thus, for a given geometry, the distribution of tractions is determined by a single matrix inversion. Given this distribution, a nonlinear differential equatio...

Generation of external electric fields by insulators as a result of electron irradiation at normal atmospheric pressure

Abstract: A phenomenological description is given of the kinetics of generation of effective densities of surface charges on a plane-parallel insulator, representing its ability to produce external electric fields after the end of electron irradiation at normal atmospheric pressure. These external electric fields are produced as a result of a relaxation of the charge accumulated in the insulator. It is shown theoretically and demonstrated experimentally that the magnitude and sign of the effective surface charge densities depend on the ratio of the maximum range of electrons in the material to the thickness of the sample and on the influence of the absorbed radiation energy on the bulk electrical conductivity of the insulator.