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Showing papers on "Field effect published in 1999"


Journal ArticleDOI
22 Oct 1999-Science
TL;DR: A solution of cadmium selenide nanocrystals was used to print inorganic thin-film transistors with field effect mobilities up to 1 square centimeter per volt second, which suggests a route to inexpensive, all-printed, high-quality inorganic logic on plastic substrates.
Abstract: A solution of cadmium selenide nanocrystals was used to print inorganic thin-film transistors with field effect mobilities up to 1 square centimeter per volt second. This mobility is an order of magnitude larger than those reported for printed organic transistors. A field effect was achieved by developing a synthesis that yielded discretely sized nanocrystals less than 2 nanometers in size, which were free of intimately bound organic capping groups. The resulting nanocrystal solution exhibited low-temperature grain growth, which formed single crystal areas encompassing hundreds of nanocrystals. This process suggests a route to inexpensive, all-printed, high-quality inorganic logic on plastic substrates.

520 citations


Patent
04 Mar 1999
TL;DR: In this paper, a field effect semiconductor device including a substrate, a dipole barrier formed on the substrate, and a channel layer formed by the dipole barriers is described.
Abstract: A field effect semiconductor device including a substrate, a dipole barrier formed on the substrate, a channel layer formed on the dipole barrier, and source, gate and drain electrodes formed on the channel layer. The dipole barrier provides a potential barrier and a maximum electric field sufficient to confine electrons to the channel layer.

95 citations


Journal ArticleDOI
TL;DR: In this paper, field effect conductance measurements were made on individual microscopic crystals of the organic semiconductor sexithiophene (6T) and the resulting wire/6T/wire structures were used in a transistor configuration to probe the in-plane conductance of the crystals as a function of transverse electric field.
Abstract: Field effect conductance measurements were made on individual microscopic crystals of the organic semiconductor sexithiophene (6T). These crystals, ranging from 1 to 6 molecules (2−14 nm) in thickness and from 1 to 2 μm in diameter, were deposited by thermal evaporation onto SiO2 substrates previously patterned with closely spaced (∼400 nm) pairs of Au wires. Atomic force microscopy (AFM) of these substrates demonstrated the growth of individual 6T crystals between the wires. The resulting wire/6T/wire structures were used in a transistor configuration to probe the in-plane conductance of the crystals as a function of transverse electric field (i.e., perpendicular to the substrate). These measurements showed (1) no discernible dependence of the carrier mobility on thicknesseven down to crystals as thin as a monolayersuggesting that much of the current is carried by the first monolayer next to the SiO2, (2) activated transport (EA = 25 meV) at temperatures above 100 K but nearly temperature-independent tra...

82 citations


Journal ArticleDOI
TL;DR: In this article, a unified model for long and short-channel polysilicon thin-film transistors (poly-Si TFTs) suitable for circuit simulation is presented.
Abstract: We present a new unified model for long and short-channel polysilicon thin-film transistors (poly-Si TFTs) suitable for circuit simulation. The model is based on the effective medium approximation and should be valid for transistors of channel lengths down to 1 μm. The model accounts for field effect mobility enhancement in the moderate inversion regime and for mobility degradation at high gate voltages, for DIBL effect, kink effect, off-state current and channel-length modulation. Good agreement between the model and the measurements was found for a wide range of channel lengths.

61 citations


Patent
Bin Yu1
03 May 1999
TL;DR: In this paper, a method of fabricating an integrated circuit with less susceptibility to gate-edge fringing field effect is disclosed, which can be used for P-channel or N-channel metal oxide field semiconductor effect transistors (MOSFETs).
Abstract: A method of fabricating an integrated circuit with less susceptibility to gate-edge fringing field effect is disclosed. The transistor includes a low-k dielectric spacer and a high-k gate dielectric. The high-k gate dielectric can be tantalum pentaoxide or titanium dioxide. The process can be utilized for P-channel or N-channel metal oxide field semiconductor effect transistors (MOSFETs).

60 citations



Journal ArticleDOI
TL;DR: In this paper, a simple model for charge carrier transport across grain boundaries with an acceptor-like trap level is proposed, where potential wells between the grains are formed due to negatively charged grain boundaries.
Abstract: A simple model is proposed for charge carrier transport across grain boundaries with an acceptor-like trap level. Potential wells between the grains are formed due to negatively charged grain boundaries. Based on this model, a variety of temperature dependencies of the charge carrier mobility can be described. Using realistic parameters, this model reproduces very well the measured temperature dependencies of the field-effect mobility in polycrystalline pentacene and oligothiophene thin film devices. Therefore, it seems to be difficult to investigate the intrinsic material properties of organic semiconductors using only polycrystalline field-effect devices, since they may be masked by the effects of traps and grain boundaries.

55 citations


Journal ArticleDOI
TL;DR: In this article, the authors reported measurements of hopping transport in modulation-doped Si field effect structures with a layer of Ge nanometer-scale dots embedded in proximity with the p-type conductive channel.
Abstract: We report measurements of hopping transport in modulation-doped Si field-effect structures with a layer of Ge nanometer-scale dots embedded in proximity with the p-type conductive channel. It is found that the activation energy of hopping conductivity in the impurity band of the doped Si layer changes with increasing quantum dot~QD! size, passing through a minimum, due to trapping of holes by the QD’s. We observed conductivity oscillations with the gate voltage which disappeared in magnetic field. The drain current modulation was attributed to hopping transport of holes through the discrete energy levels of the Ge nanocrystals. Field-effect measurements in structures which contain as many as 10 9 dots enable us to resolve as wellpronounced maxima in G2Vg characteristics the single-electron charging of each dot with up to six holes. The level structure reveals up to three distinct shells which are interpreted as the s-like ground state, the first excited p-like state and the second excited d-like state. We are able to obtain the hole correlation ~charging! energies in the ground and first exited states, the quantization energies and the localization lengths. @S0163-1829 ~99!08819-0#

33 citations


Patent
17 Nov 1999
TL;DR: In this article, the authors propose a vertical-channel trench-substrate field effect device (VVFED) that allows the substrate current exiting a MOSFET structure to be independently and controllably tuned.
Abstract: A semiconductor device that provides for substrate current exiting a MOSFET structure, and hence the performance thereof, to be independently and controllably tuned. The semiconductor device includes a semiconductor substrate of a first conductivity type, a conventional MOSFET structure disposed thereon, and at least one vertical-channel trench-substrate field effect device disposed in the semiconductor substrate. The vertical-channel trench-substrate field effect device includes a vertical-channel region beneath the MOSFET structure. During operation, substrate current exiting the MOSFET structure can be independently and controllably tuned by applying a potential bias to the vertical-channel trench-substrate field effect device that “pinches-off” the vertical-channel region. The vertical-channel trench-substrate field effect device includes an expanded trench that extends from an upper surface of the semiconductor substrate to beneath the MOSFET structure and a dielectric shallow trench spacer (e.g., silicon dioxide or silicon nitride dielectric shallow trench spacer) that is disposed along an upper portion of the sidewall of the expanded trench. The vertical-channel trench-substrate field effect device also includes a SiO2 trench liner layer disposed on those portions of the sidewall of the expanded trench that are not covered by the dielectric shallow trench spacer, and an electrically conductive trench fill layer (e.g., in-situ doped polysilicon) in the expanded trench. The vertical-channel region can be “pinched-off,” and the substrate current exiting the MOSFET structure independently and controllably tuned, by applying a potential bias to the electrically conductive trench fill layer. Also, a process for manufacturing the semiconductor device that is compatible with conventional IC manufacturing techniques.

28 citations


Proceedings ArticleDOI
23 Jun 1999
TL;DR: In this paper, the authors reported pentacene-based organic thin film transistors with field effect mobility as large as 2.1 cm/sup 2/V-s.
Abstract: We report pentacene-based organic thin film transistors (OTFTs) with field effect mobility as large as 2.1 cm/sup 2//V-s. To our best knowledge this is the highest field-effect mobility reported for an OTFT.

27 citations


Patent
14 Sep 1999
TL;DR: In this paper, the authors proposed to eliminate the influence of a surface level, and to reduce ON resistance in a GaN-system field effect transistor, by forming an insulating film on an exposed metal end face.
Abstract: PROBLEM TO BE SOLVED: To eliminate the influence of a surface level, and to reduce ON resistance in a GaN-system field effect transistor. SOLUTION: On an n-type AlGaN charge supply layer 4 of a field effect transistor, drain electrode metal 5, source electrode metal 6, and a passivation film 7 are formed. Only at a gate, the drain electrode metal 5, the source electrode metal 6, and the passivation film 7 are eliminated, an insulating film is formed on an exposed metal end face, and a gate electrode 8 is deposited at an opening part.

Journal ArticleDOI
TL;DR: The response to a parallel magnetic field of the very dilute insulating two-dimensional system of electrons in silicon metal-oxide-semiconductor field effect transistors is dramatic and similar to that found on the conducting side of the metal-insulator transition as mentioned in this paper.
Abstract: The response to a parallel magnetic field of the very dilute insulating two-dimensional system of electrons in silicon metal-oxide-semiconductor field-effect transistors is dramatic and similar to that found on the conducting side of the metal-insulator transition: there is a large initial increase in resistivity with increasing field, followed by saturation to a value that is approximately constant above a characteristic magnetic field of about 1 T. This is unexpected behavior in an insulator that exhibits Efros-Shklovskii variable-range hopping in zero field, and appears to be a general feature of very dilute electron systems. {copyright} {ital 1999} {ital The American Physical Society}

Journal ArticleDOI
TL;DR: In this paper, the structure and vibrational properties of the Si(100)-H(2×1) surface in an electric field were investigated and the results showed that inelastic scattering events with energy transfer nℏω, where n > 1, play an important role in the desorption process.

Journal ArticleDOI
TL;DR: In this paper, the influence of oxygen on the electrical parameters of a copper phthalocyanine thin film field effect transistor was investigated by means of temperature-modulated field effect spectroscopy.
Abstract: The influence of oxygen on the electrical parameters of a copper phthalocyanine thin film field effect transistor was investigated by means of temperature-modulated field effect spectroscopy. It was found that both the dark electrical conductivity and threshold voltage of the source–drain current versus gate voltage dependence were changed after oxygen exposure. Both effects can be effectively utilised for gas sensing. Copyright © 1999 John Wiley & Sons, Ltd.

Journal ArticleDOI
TL;DR: In this article, the relationship between transistor performance and the electronic properties of the polaronic charge carriers probed by electro-optical modulation spectroscopy was investigated in order to understand the transport physics of this high mobility polymer.

Journal ArticleDOI
TL;DR: In this paper, the flow of current through undoped polysilicon is analyzed, where charge is assumed to be trapped in grain boundaries giving potential barriers across which the free electrons and holes pass.

Journal ArticleDOI
TL;DR: The theoretical phase diagrams of a magnetic lattice fluid in an external magnetic field are presented in this article, where it is shown that, depending on the strength of the nonmagnetic interaction between particles, various effects of the external field on the Ising fluid take place.
Abstract: The theoretical phase diagrams of a magnetic (Ising) lattice fluid in an external magnetic field are presented. It is shown that, depending on the strength of the nonmagnetic interaction between particles, various effects of the external field on the Ising fluid take place. In particular, at moderate values of the nonmagnetic attraction the field effect on the gas-liquid critical temperature is nonmonotonic. A justification of such behavior is given. If short-range correlations are taken into account (within a cluster approach), the Curie temperature also depends on the nonmagnetic interaction strength.

Journal ArticleDOI
TL;DR: In this article, a deep level, the ES1, introduced in n-GaN by sputterdeposition of gold Schottky contacts exhibits metastable-like behavior during temperature cycling between 55 and 250 K.
Abstract: We show that a deep level, the ES1, introduced in n-GaN by sputter-deposition of gold Schottky contacts exhibits metastable-like behaviour during temperature cycling between 55 and 250 K. The ES1 has an energy level 0.22±0.02 eV below the conduction band. We provide some evidence that indicates that the defect responsible for the ES1 has a second energy level, the ES1∗, and that the metastable behaviour of the ES1 may be due to negative-U ordering of these two energy levels. Furthermore, field effect measurements indicate that the ES1 level has a donor character, while the ES1∗ level is probably an acceptor.

Journal ArticleDOI
TL;DR: In this article, the effect of microwave field on the kinetics of recombination fluorescence from nonpolar solutions irradiated with nanosecond X-ray pulses is described.

Journal ArticleDOI
TL;DR: In this article, the amplitude and lifetime of the slow component of fluorescence are additionally reduced by an external microwave field, at a microwave frequency of 9400 MHz, a constant magnetic field of 0.3295 T and an oxalylfluoride pressure of 30 mTorr.
Abstract: Time-resolved measurements of the microwave field effect using optically detected EPR (ODEPR) have demonstrated that the amplitude and lifetime of the slow component of fluorescence are additionally reduced by an external microwave field, at a microwave frequency of 9400 MHz, a constant magnetic field of 0.3295 T and an oxalylfluoride pressure of 30 mTorr. This is accompanied by an increase in the fast component amplitude, at a constant decay rate of (2.36 × 0.19) 107 s−1. The fluorescence intensity was found to decrease, and phosphorescence intensity to increase, with subsequent saturation at higher microwave intensities. The experimental data are interpreted using the indirect mechanism theory in the limit of low-level density.

Journal ArticleDOI
TL;DR: In this article, the effect of the space charge of emitted electrons on the electric field at the tip of a field emitter was considered and the Poisson equation was solved numerically for a spherical vacuum diode with a field emission cathode.
Abstract: The paper considers the effect of the space charge of emitted electrons on the electric field at the tip of a field emitter. To analyze this phenomenon, the Poisson equation was solved numerically for a spherical vacuum diode with a field emission cathode. The dependence of the electric field on the geometric field has been compared with the known approximate dependencies, Strong screening of the electric field at the cathode by the space charge of emitted electrons at fields >5/spl times/10/sup 7/ V/cm is noted. Based on the obtained dependencies of the actual field on the geometric one and using the SuperSAM code, the field emission occurring in a Muller projector has been simulated. It has been shown that the "ring effect" appearing in field emission patterns can well be explained by field emission from the peripheral regions of the field emitter. The current density distributions over the surface and in the bulk of the emitter have been analyzed.

Journal ArticleDOI
TL;DR: In this article, the electron mobility of hexadecafluorophthalocyaninato-copper (F16PcCu) films was evaluated based on field effect measurements in vacuum and in various gas atmospheres.
Abstract: The electron mobility of hexadecafluorophthalocyaninato-copper (F16PcCu) films was evaluated based on field effect measurements in vacuum and in various gas atmospheres. An Arrhenius plot of the mobility showed that the carrier transport followed a thermally activated hopping mechanism with an activation energy of 0.28 eV. The mobility evaluated for freshly prepared films in ultrahigh vacuum was 2.0 × 10−3cm2V−1s−1 at room temperature. The electrical conductivity and carrier density were 4.4 × 10−5S cm−1 and 1.4 × 1017cm−3 respectively. The high carrier density indicated the existence of impurities acting as electron donors in the films. The field effect carrier mobility increased to 5.7 × 10−3cm2V−1s−1 in NH3 atmosphere (100%, 1 atm) and decreased by 75% in the presence of O2 gas (100%, 1 atm). A quick recovery of mobility was observed when the gas molecules were evacuated, indicating a low capability of gas adsorption.

Journal ArticleDOI
T. Suga1, Masaaki Iizuka1, S. Kuniyoshi1, Kazuhiro Kudo1, Kuniaki Tanaka1 
TL;DR: In this article, the authors have fabricated thin-film field effect transistors (TFTs) using perylene derivatives (PTCDI, BPPC) and estimated electrical parameters such as carrier mobility, carrier concentration and electrical conductivity by in-situ field effect measurements.

Journal ArticleDOI
TL;DR: In this paper, a comparative analysis of electrical characteristics of 4H- and 6H-SiC metal-oxide-semiconductor field effect transisitsors (MOSFETs) is presented.
Abstract: This paper reports a comparative investigation of electrical characteristics of 4H- and 6H-SiC metal-oxide-semiconductor field effect transisitsors (MOSFETs). From the study of C–V measurement, no significant difference is found between p-type 6H-SiC and 4H-SiC in the dependence of the oxidation process, such as wet or dry ambient. Nevertheless, the MOSFETs characteristics are quite different, and a very small field effect mobility μeff (<10 cm2 (V s)−1) is obtained for 4H-SiC. This poor μeff is improved by H2 surface annealing, which has been reported to give atomically flat surface, and mono-hydride termination. In addition, a strong correlation is found between μeff and the shift of the threshold voltage from the ideal value. These results confirm that the surface preparation technique is a key factor to control the interface. And H2 treatment reduces the negative charges at the interface and results in a μeff of 20 cm2 (V s)−1 in 4H-SiC MOSFETs.

Patent
19 Mar 1999
TL;DR: In this article, the authors proposed a process for the crystallization of a semiconductor film by a laser and to improve a process margin in the process for producing a liquid crystal display device which is integrated with peripheral circuits.
Abstract: PROBLEM TO BE SOLVED: To improve throughput, when carrying out crystallization of a semiconductor film by a laser and to improve a process margin in a process for producing a liquid crystal display device which is integrated with peripheral circuits. SOLUTION: This process includes a stage for forming a first semiconductor film, having first field effect mobility by a fixed phase growth method on direct deposition method on a substrate 1 having a display region 2a, a first peripheral circuit region 3a and a second peripheral circuit region 4a, a stage for changing the semiconductor film to the second semiconductor film, having second electric field effect mobility by irradiating the first semiconductor film on the first peripheral circuit region 3a with a first linear or two-dimensional laser beam at a first energy density, and a stage for changing the first semiconductor film to a third semiconductor film, having the third electric field effect mobility by irradiating the first semiconductor film on the second peripheral circuit region with a second linear or two-dimensional laser beam at a second energy density which is different from the first energy density.

Journal ArticleDOI
TL;DR: In this paper, the effect of an electric field E = 120 MV m-1 on the critical current Ic and the currentvoltage characteristics of yttrium-based high-Tc ceramics have been studied experimentally with data on the electric field effect related to the criticalcurrent behaviour with temperature near the critical temperature Tc.
Abstract: The effect of an electric field E = 120 MV m-1 on the critical current Ic and the current-voltage characteristics of yttrium-based high-Tc ceramics have been studied experimentally with data on the electric field effect related to the critical current behaviour with temperature near the critical temperature Tc. The objects of study were ceramics with stoichiometric composition YBa2Cu3Oy, fabricated in different sintering conditions (123-I and 123-II samples), copper-deficient YBa2Cu3-xOy (D samples) and YBa2Cu3-xOy/Agx ceramics (S samples with silver present in amount equal to the copper deficiency 0 Ic, whereas in S and 123-II samples no field effect is observed. The results of the measurements of the temperature dependence of Ic near the critical temperature confirmed the presence of superconductor-insulator-superconductor tunnel intergrain junctions (SIS) in D and 123-I samples, and superconductor-normal metal-superconductor proximity junctions (SNS) in S and 123-II samples. The conclusion is drawn that the electric-field effect correlates with the existence of SIS-type weak links at grain boundaries in the ceramic.

Journal ArticleDOI
TL;DR: In this article, the specific example of hydrogen abstraction from a diamond(111) surface is studied using a cluster model and it is shown that the barrier is not only related to the position of the ionic and covalent asymptotes, but also the addition of nearby atoms in both the parallel and perpendicular direction to the electric field is found to have an effect.

Journal ArticleDOI
TL;DR: In this article, the authors measured the temperature and magnetic field dependence of the in-plane thermal conductivity κ(T, B) of high-temperature superconducting crystals, at different orientations of the magnetic field.
Abstract: We have measured the temperature (10 K≤T≤150 K) and magnetic field (B≤9 T) dependence of the in-plane thermal conductivity κ(T, B) of YBa2Cu3O7−x(Y123), YBa2Cu4O8(Y124), and Bi2Sr2CaCu2O8(Bi2212) high-temperature superconducting crystals, at different orientations of the magnetic fieldB∥cand ⊥c). Our results show that κ depends on field below and above the critical temperature due to the contribution of superconducting fluctuations and of vortices and orbital effects to the scattering of quasiparticles or electrons. Within experimental resolution no dimensional crossover of the superconducting fluctuations can be clearly recognized. Qualitative and quantitative differences in the field dependence between the crystals are observed and discussed. We argue that the anisotropy plays a mayor role in the relative weight between the different scattering processes and the field effect on the occupation number of quasiparticles, determining the field dependence of the thermal conductivity in these cuprates. In particular we found that k increases with field in a Bi2212 crystal forB⊥cand at T<20 K.

Posted Content
TL;DR: In this article, it is proposed to use the field effect as a basic property specifying the difference between an insulator and a conductor, a static phenomenon which absent in the former but present in the latter.
Abstract: It is proposed to used, as a basic property specifying the difference between an insulator and a conductor, a static phenomenon, namely the field effect which absent in the former, but present in the latter. The absence or present of the field effect is closely associated with the nature of the homogenious linear response to a static electric field. For an insulator, it is finite; for a conductor, it depends on the volume V and tends to infinity when V to infinity. The fluctuation-dissipation theorem makes it possibile to relate the nature of this response to the mean square fluctuation of the dipole moment of the system, which is normal in an insulator, but anomalious in a conductor. A number of examples are considered. A notable property of the BCS supercondctivity state have remarked, namely: its conductivity property is a consequence of non-zero electron density fluctuations in the ground state of the system with ODLRO.

Journal ArticleDOI
TL;DR: In this paper, the effect of reverse bias field and forward pulse on the trap concentration of the deep levels in semiconductors has been investigated and a more exact formulation than used previously has been developed.
Abstract: To determine the trap concentration of the deep levels in semiconductors, more exact formulation than used previously has been developed. As an example, we have selected molecular beam epitaxy-grown, Si-doped, low temperature (LT) GaAs and considered the λ effect. The effect of reverse bias field and forward pulse on the deep level trap concentrations has been investigated. Experimental data were obtained from the field effect deep level transient spectroscopy measurement and capacitance voltage characteristics at appropriate temperatures. The LT-GaAs was found to possess rather high trap concentrations in all the deep levels included in the present investigation.