Search

The paper presents the experimental results on temperature dependences of electrical resistance of disordered single-walled carbon nanotube (SWNT) films on polyethylene terephthalate (PET) substrates and discusses the piezoresistive effect studied in the films within the strain ranging from –0.15% to +0.15%. The nanotubes were prepared by catalytic disproportionation of carbon monoxide on Fe particles obtained by ferrocene vapor decomposition. SWNT films were prepared by their in situ deposition on silicon substrates and transferred to PET substrates. Electron transport properties were studied from room temperature down to 77.4 K. It is shown that the experimental data are described by the fluctuation-induced tunneling conduction model. The effective activation energy estimated by approximating experimental data varies from 175 meV to 6.5 meV for the samples with the time of nanotube deposition varying from 5 min to 120 min, respectively. The strain gauge factor measured in the film with the smallest sheet electrical resistance appeared to be negative and equal to –14.

The temperature dependences of the conductivity and thermoelectric power for a series of samples W1–x Nb x S2, W1–x Nb x Se2, WS2–y Se y , W1–x Nb x S2–y Se y are studied at low temperatures. It is found that the cation substitution of W atoms with Nb leads to an increase in the conductivity and a decrease in the thermoelectric power. The anion substitution of S with Se atoms results in a simultaneous increase in the conductivity and thermoelectric power. The highest power factor among the samples studied is inherent to W0.8Nb0.2Se2.

The paper reports on the strain sensitivity of molybdenum–rhenium disulfide films and their resistance temperature characteristics. The polycrystalline sample of composition Mo0.95Re0.05S2 was synthesized by direct high temperature reaction of elements with stoichiometric ratio. Thin films were prepared using two methods – spray and vacuum filtration of colloidal dispersions of Mo0.95Re0.05S2. The strain gauge factors, of 12 and 20, respectively, were observed depending on the preparation method. The samples were examined for endurance and the strain gauge factors remained without significant degradation during 105 load cycles at least. In order to estimate effective activation energies the resistance temperature characteristics have been measured to be 150 meV for the samples sprayed and 200 meV for those filtered.

The paper reports experimental study of piezoresistive effect in composite films based on polybenzimidazole with few-layered graphene nanoparticles filler. Colloidal dispersions of few-layered graphene (FLG) were obtained by ultrasonic treatment of synthesized FLG in the solution of poly[2,2′-(p-oxydiphenylen)-5,52′-bisbenzimidazole] (OPBI) in N-methyl-2-pyrrolidone (NMP). Electroconductive films were formed from the dispersions by flow coating. To investigate dependence of electrical resistance on mechanical strain strips of the films were bonded onto beams of uniform strength (in bending) with cyanoacrylate adhesive, the beams being insulated with polymer glue. The strain gauge factors were measured for two films with filler content being 0.75 and 2.00 mass per cent. Electrical resistances were measured by two- and four-point methods, the factors being independent on the method used. The factors are the same within the error for both filler contents and equal to 21 on average.

Possible application of tungsten dichalcogenides as gas-sensing elements is discussed in this paper. The experimental results on sensitivity of pristine and niobium doped WS2 and WSe2 to acetone and ethanol gases are presented. Polycrystalline powder specimens were obtained by high temperature solid-state synthesis from the stoichiometric mixture of pure elements. Two types of samples were studied: 1) tablets pressed at 1.5 GPa to form bulk samples and 2) thin films prepared from 35% ethanol-water colloidal dispersions by their filtration onto membrane filters (pore diameter is 20 nm). The electrical resistances of the samples were shown to be increased in the presence of ethanol and acetone gases at room temperature, thereby revealing positive response to reducing gases.

The thermoelectric properties of polycrystalline materials on the base of WS2 with Nb partial replacement of metal atoms W have been researched in this work. The temperature characteristics of the materials have been measured in the temperature range from 77 to 300 K. We have found that replacement of metal atoms W partly with Nb significantly increases the electrical conductivity and decreases the Seebeck coefficient. The best stoichiometric ratio in terms of the thermoelectric properties has had material W0.90Nb0.10S2. This material has had a value of power factor 32 μW/m2·K.

The paper reports on electron transport properties of tungsten disulphide doped with rhenium: WS2, W0.95Re0.05S2, W0.90Re0.10S2 and W0.85Re0.15S2. Polycrystalline powders of the compositions were synthesized by direct high temperature reactions of elements with stoichiometric rations. Experimental samples were formed of the powders by conventional compress technology at a pressure of 1.5 GPa. The measured temperature dependences of conductivity are typical for fluctuation induced tunnelling conduction. The band gaps were estimated from the dependences and the gaps lie in the range from 100 to 400 meV for different compositions.

Transition metal chalcogenides are perspective thermoelectric materials which have a great interest for application. In this work, the polycrystalline bulk WS2 and solid solutions WS2−ySey types have been studied. In contrast to the literature data obtained at higher temperatures, we have investigated the thermoelectric properties of these materials at low and middle temperatures (77–450K). The temperature dependences of electrical conductivity and Seebeck coefficient were received from experimental data. The Seebeck coefficients of these materials have a high values, the maximum value up to 2000 μ V/K has been obtained.

In the past years, fundaments were set for a new type of electronics which is based on tracks in insulators formed by individual or multiple swift heavy ions. Due to the possibility of inserting any (semi)conducting material into these tracks, various active and passive electronic devices can be created. Among them are also transistor-like and Esaki diode-like elements. As many of these structures have sensing properties and the capability to undergo logic decisions, autonomous intelligent sensors appear to be a favourite field for future application. The use of liquid conductors may even expand the range of applicability towards medical implants.

With interest rising recently in nanostructures of all kinds, attention was also given to etched ion tracks in insulators. The emerging nanopores with a very high aspect ratio enable one to create new functionalities, especially in thin polymeric foils and oxide-on-silicon structures, when combined with electronic, optical, catalytic or sensing materials. These materials are often inserted into the nanopores in the form of nanoparticles for several reasons. On the one hand, quantum effects can easily be exploited in this way, and, on the other hand, tailoring of size and distance of (semi)conducting nanoclusters enables one to obtain any desired conductivity value between insulating and metallic nanocluster/nanopore devices. Also, the very large surface areas of nanoclustered materials may be useful for initiating chemical reactions, e.g. for sensing, catalytic, or medical purposes. Nanotubes may be grown within the nanopores, which enhance the range of possibilities greatly. Potential applications of the...

Carbon nanotubes (CNTs) were selectively grown in etched ion tracks in SiO 2 layers on Si . For this sake, Ni -catalyst nanocrystals were initially deposited within the ion tracks by galvanic deposition. The characteristics of plasma-enhanced chemical vapor deposition (PECVD)- and thermal chemical vapor deposition (TCVD)-grown CNTs, such as structural details and length distribution, were investigated. In addition, field emission properties were studied. The analysis revealed that the emerging PECVD-grown CNTs were of cylindrical and/or conical shape and usually had diameters as large as the etched tracks. The exponential length distribution of these CNTs can be well understood by applying a simple defect-growth model. For contrast, many narrow and curled CNTs were found to cluster in spots well separated from each other, after applying TCVD instead of PECVD. The Raman investigations of PECVD-grown CNTs showed that Si – O – C and Si – C phases had formed during the growth of the CNTs. These ion-track-correlated PECVD-grown CNTs open the way for the production of novel 3D nanoelectronic devices based on the TEMPOS concept. These structures are also excellent candidates for experiments on channeling in CNTs. Application as field emitting devices, however, appears unfavorable due to poor mean-field enhancement factors and insufficient stability.

In this work, we have investigated the sub-surface-layers of porous SiO2 templates, in which emerge the possibility of carbon nanotube (CNTs) inter-connections. CNTs were grown in Co-catalyst doped, cubic, porous SiO2 templates using thermal — as well as dc-PECVD. The as-grown templates were sonicated to remove the over-layer CNTs, and then underwent chemical etching. The etched templates were characterized by atomic force microscopy (AFM) which showed patterned structures on the surface. Raman spectrum of these structures was found to be identical to that of the CNTs. The analysis revealed that horizontally patterned CNTs were grown in the pores of SiO2 templates in sub-surface region of the templates. The CNTs grown in sub-layers of template were termed as buried-layer CNTs. In dc-PECVD treatment, under excess arcing conditions, the porous template became separated from the Pt/Si substrate and lifted up. As a result, vertically-aligned CNTs were generated over, as well as under, the lifted template layers. This lifting-up phenomenon was attributed to the dissociation of plasma-energy preferentially at the interface sites of SiO2–Pt/Si. Possible mechanisms for this phenomenon are discussed. We speculate that buried-layer CNTs can simultaneously be inter-linked to the over-layer CNTs, the lifted template and the substrate, which could be useful for generating three-dimensional CNT-networks in the skeleton of cubic porous SiO2 templates.

The work presents a study of piezoresistive effect of thin films of rhenium-doped molybdenum disulfide of composition Mo 0.95 Re 0.05 S 2 possessing layered structure of 2H-MoS 2 type. The compound was synthesized by high temperature ampoule method using stoichiometric mixture of elements. The thin films were formed by spraying colloidal dispersion produced by liquid exfoliation of solid phase in mixed solvent EtOH/H 2 O. The phase Mo 0.95 Re 0.05 S 2 is semiconductor with effective activation energy of about 150 meV estimated from temperature dependences of resistance of the films. The dependence of resistance on deformation is presented. It has almost linear type and good reproducibility during a sinusoidal alternating load of 0.12% deformation amplitude. The strain gauge factor of 12 and 24 was obtained depending on preparation details from room temperature measurements using a beam of uniform strength (in bending).

Transition-metal chalcogenides are prospective thermoelectric materials. One of them is a molybdenum disulfide MoS 2 , which has a layered structure. MoS 2 has a good potential to have a high value of thermoelectric quality factor due to a high value of thermo-EMF and low value of thermal conductivity. But a low value of its electrical conductivity suppresses the thermoelectric quality factor ZT on the level of 0.1 at high temperatures. Present work shows the influence of metal addition to MoS 2 on electrical conductivity and Seebeck coefficient (SC) of final mixture. Mo 2 S 3 was chosen as a metal addition. Mo 2 S 3 has an electrical conductivity of 330 S/m and thermo-EMF of 10 µV/K at 300K. Bulk powder samples of MoS 2 with addition of 3, 6, 10, 30 and 60 wt% Mo 2 S 3 were studied. An electrical conductivity of samples was measured in temperature range: 77 K – 423 K. All samples have shown semiconductor hopping conductivity with variable hopping length. The SC was measured in the temperature range of 300K – 500K. The addition of Mo 2 S 3 decrease SC from 300µV/K to 75µV/K.

We introduced a simple fabrication process for field emission devices based on carbon nanotubes (CNTs) emitters. Instead of using the ITO material as a transparent electrode, a metal (Au) with thickness of 5–20 nm was used. Moreover, the ITO patterning process was eliminated by depositing metal layer, before the CNT printing process. In addition, the thin metal layer on a photoresist (PR) layer was used as UV block. We fabricated the CNT field emission arrays of triode structure with a simple process. And I–V characteristics of field emission arrays were measured. The maximum current density of 254 μA/cm2 was achieved when the gate and the anode voltages were kept 150 and 3000 V, respectively. The distance between anode and cathode was kept constant.

MWNT/nylon 6, 6 composite nanofibers were fabricated using an electrospinning method, and the electrical properties were examined as a function of the filler concentration. Initially, the pristine, purified MWNTs were treated with a 3:1 mixture of concentrated H2SO4/HNO3 to introduce carboxyl groups onto the MWNT surface. The carboxylated MWNTs were then treated with thionyl chloride and an ethylenediamine solution for amide functionalization. FT-IR spectroscopy was used to examine the functionalization of the MWNTs. Nylon 6, 6 is readily soluble in formic acid. Therefore, the amide functionalized MWNTs were dispersed in formic acid. The solution remained stable and uniform for more than 40 h. –NH2 termination of the MWNTs improved the dispersion stability of the MWNTs in formic acid. The MWNTs-suspended in a solution of nylon 6, 6 in formic acid was electrospun to obtain the nanofibers. The electrical properties of the nanofibers were examined as a function of the filler concentration. The results showed that the I–V properties of the nanofiber sheet improved with increasing filler concentration.

We report on the correlation between the concentration of Fe-catalyst, doped in the aluminum phosphate (AlPO4-5) zeolite and the resulting density of carbon nanotubes (CNTs) to obtain the optimum electron field emission conditions from the CNTs. Initially, AlPO4-5 crystallites were impregnated, for a period of ∼ 10–60 min, in the Fe-catalyst solution and subjected to Electron Spectroscopy for Chemical Analysis (E.S.C.A.). The analysis revealed that the concentration of Fe-catalyst, CFe, was increased from ∼ 1.7% to ∼ 8.6%, respectively, with increase in impregnation time, IT. The HRTEM results showed that Fe nano-clusters, with diameter ∼ 7–10 nm, were formed in the surface region of the crystallites. These crystallites were sprayed on the conducting substrates, under identical spraying conditions. SEM study revealed that the coverage of the crystallites on the substrates was ∼ 103–104 crystallites/cm2. These substrates were subjected to direct current plasma enhanced chemical vapor deposition (dc-PECVD) process, to grow CNTs. The SEM micrographs were recorded for the CNT-grown substrates and the average areal density of CNTs, (σT)av, on the crystallites (t/cm2) was estimated. The analysis indicated that (σT)av increased from ∼ 6.24 ± 0.19 × 1010 to 2.04 ± 0.61 × 1011 t/cm2 with gradual increase in CFe. The field emission study of the samples revealed that the optimum values of the turn-on electric field, ∼ 3.69 V/μm and the field emission current density, ρd, ∼ 1.78 × 103 μA/cm2 were achieved for (σT)av, ∼ 6.24 ± 0.19 × 1010 t/cm2, at a concentration of Fe, CFe, ∼ 3.0%, encapsulated in the AlPO4-5 crystallites.

The simulation results of the electric field intensity and the enhancement factor, γ, for an individual CNT imaged as a conducting rod is presented. The field enhancement factor, γ, for the CNT paste array is evaluated experimentally by varying the cathode-anode (CA) spacing, d. The simulations indicate that the distribution of electric field intensity and the enhancement factor as a function of cathode-anode spacing, d, could be divided into the two parts: strong (d 100 μm) dependences of the enhancement factor γ(d). Furthermore, the field enhancement factor, γ, estimated experimentally for the CNT paste FEA indicates that the two-region field emission model (TRFE) is adequate for estimation of the field enhancement factor, γ. Moreover, the effective enhancement factor, γ, for the CNT paste FEA was found to be ≈50γ and is attributed to the additions of the emission currents from the individual CNTs in an array. In addition, the empiric functions of the geometrical enhancement factor, β(d), and γ(d) were estimated from the Fowler–Nordheim plot for the CNT paste FEA. One can use the empiric functions β(d) and γ(d) for the design and fabrication of the devices based on the CNT paste FEA with a variable CA spacing.

We investigated under-gate type carbon nanotube field emitter arrays (FEAs) for back light unit (BLU) in liquid crystal display (LCD). Gate oxide was formed by wet etching of ITO coated glass substrate instead of depositing SiO2 on the glass substrate. Wet etching is easier and simpler than depositing and etching thick gate oxide to isolate the gate metal from cathode electrode in triode. To optimize the triode, we simulated the electric field distribution and electron trajectory in triode structures by the SIMION simulator. CNT emitters were formed using screen printing of photosensitive CNT paste. Field-emission characteristics of triode structure were measured. The maximum current density of 92.5 μA/cm2 was when the gate and anode voltage was 95 and 2500 V, respectively, at the anode–cathode spacing of 1500 μm.

The growth of carbon nanotubes (CNTs) were evidently observed, at the channel ends of the mesoporous SAPO4-5 zeolites. The Fe-catalyst SAPO4-5 crystallites prepared by the sol–gel method were employed to the thermal CVD process, at a temperature ∼650 °C for 30 min, using the mixture of acetylene and ammonia gases. The recorded SEM images show the formation of well aligned MWNTs at the channel ends of the crystallites. The analysis of HRTEM shows that, the outer diameter of CNTs varies in the range of 25–27 nm, whereas, the inner diameter varies in the range of 14–17 nm. The diameter of the CNTs was found to be varied marginally as compared to that of the channel diameter of the SAPO4-5 crystallite. Furthermore, the observed formation of CNTs, along the ab-plane, could either be originated at a depth from the channels or at the channel ends of the crystallites. Although the former is attributed to the precipitation of the Fe-catalyst in the channels, the later is thought to be due to the out diffusion and clustering of Fe-atoms near the channel ends of the crystallites. The recorded micro-Raman spectrum showed the small ratio of, I(D) / I(G), which suggest that, the synthesized tubes are of high quality with less amount of defects.

In the last years, concepts have been developed to use etched ion tracks in insulators, such as polymer foils or silicon oxide layers as hosts for nano- and microelectronic structures. Depending on their etching procedure and the thickness of the insulating layer in which they are embedded, such tracks have typical diameters between some 10 nm and a few μm and lengths between some 100 nm and some 10 μm. Due to their extremely high aspect ratios, and due to the possibility to cover very large sample areas, they exceed the potential of nanolithography.In this paper, the strategies of etched ion track manipulation are briefly outlined, that lead to the formation of nanotubules, nanowires, or tubular arrangements of nanoclusters. Examples where nanoelectronic structures are based on single ion tracks, are nanocondensors or sensors for temperature, light, pressure, humidity and/or alcohol vapor. By combination of ion track metallization and conducting track-to-track connections on the foil surface, micromagnets, microtransformers and microcondensors could be formed within polymer foils.Finally, we present our new "TEMPOS" (Tunable Electronic Material with Pores in Oxide on Silicon) concept where nanometric pores, produced by etching of tracks in silicon oxide on silicon wafers, are used as charge extraction (or injection) channels. In comparison with the metal oxide semiconductor field effect transistors (MOS-FETs), the TEMPOS structures have a number of additional parameters (such as the track diameter, density, and shape, and the material embedded therein and its spatial distribution) which makes these novel structures much more complex. This eventually leads to higher compactation of the TEMPOS circuits and to unexpected electronic properties. TEMPOS structures can overtake the function of tunable resistors, condensors, photocells, hygrocells, diodes, sensors, and other elements. As an example, some corresponding current/voltage relations and TEMPOS circuits are presented. In this work we concentrate on TEMPOS structures with fullerene and phthalocyanine. Though not yet verified, TEMPOS structures could, in principle, be scaled down to nanometer sizes.

We studied the growth characteristics of carbon nanotubes which were grown from the uniformly dispersed iron nanoparticles prepared from iron acetate [Fe(II)(CH3COO)2]. The density of CNT was controlled from precursor concentrations. We also investigated the field emission properties of CNTs. We found that the optimization of CNT density is an important factor for field emission properties. Patterning process of iron acetate was achieved simply by alkaline solution.

To search for structural changes of molybdenum disulphide (MoS2) nano-powder under thermal treatment, the annealing of the powder was carried out in vacuum or in argon. MoS2 powder with a grain size of 3–5 nm was synthesized by a chemical method. The temperature of annealing was varied in the range of 380–1000 °C. The time of annealing was varied in the range from 4 h (380 °C) to 5 min (1000 °C). X-ray diffraction and transmission electron microscopy analyses were made to see the character of the change of the crystallization process and the curvature of (002) MoS2 planes. The increase of crystalline phase and the decrease of amorphous phase in the powder appears as a result of the rise of the annealing temperature. The sample annealed at Tann=380 °C and 500 °C has a small curvature of (002) planes and more enlarged grains in comparison with non-annealed MoS2 powder. The increase of the annealing temperature to Tann=700 °C leads to a strong curvature of the (002) planes. The character of the curved planes varies from quite long planes with a large radius of curvature to right-angle-form and U-form structures. The increase of the annealing temperature to Tann=1000 °C leads to a strong crystallization of the powder and a reduction of the amorphous phase.

Au/C60/p-Si sandwich structures can be easily obtained by evaporation of a thin fullerite (C60) film on a silicon substrate and a thin Au film on top of the C60 film. In this case a C60/p-Si p–n heterojunction appears. Both the dark and photoconductivities of the planar pristine and irradiated Au/C60/p-Si structures were measured as a function of the irradiation fluence. Furthermore, the pressure dependence of these structures was determined. A strong dependence on the irradiation damage was found.

We report on the technology of formation of sandwich structures based on fullerite films and on experimental results in research of optical and conductivity properties of these sandwich samples. Single crystals of sapphire (100) or silicon were used as substrates. The sandwich specimens were based on the structure M//M (M

It is known that the conductivity of fullerite depends on the applied pressure. In this paper we compare the variation of conductivity of three different fullerite structure with pressure. We examined powder, filled into thin glass capillaries and also studied fullerite nanotubules produced within etched swift heavy ion tracks in polymer foils. These investigations are compared with the results of planar Si--Au structures.

The possibility to use powder consisting of fullerite microcrystallines as a device sensitive to the external axial mechanical load is considered. We suppose that the change of conductivity of fullerite microcrystalline powder as a function of external mechanical stress will be useful for the creation of nanoscale devices of sensor electronics. This new effect based on changing of intermolecular distance between fullerene molecules due to the action of external mechanical force, which can change the distance between fullerene molecules because of weak van der Waals interaction exists. The founded effect is quite linear and sensitive to external mechanical stress is better then in well-known pressure transducers is based on silicon technology.

Gold-fullerite [C60]-silicon (p-type) sandwich structures have been fabricated in order to investigate intrinsic cross-sectional and planar electronic conductive properties, in particular the C60/p-Si p–n heterojunction. The turn-on voltage of this p–n heterojunction lies in the range 0.25–0.27 V. The I–V characteristics of the Au/C60/p-Si structure are mostly defined by the bulk specific resistance of the fullerite crystal film itself (∼6×107 Ω cm). I–V curves in the C60/Au/p-Si structure are shown to be ohmic. Au/C60/p-Si sandwiches irradiated with swift (300 MeV) heavy ions, (84Kr14+) to a total fluence ∼1010 ion/cm2 yield structures which are sensitive to ambient air pressure, specifically in the case of a transverse contact configuration, and if one of the contacts is located on the irradiated part of the fullerite film. The sandwich-structure sensitivity to pressure is ∼5×10−6 Pa−1. This exceeds the sensitivity of conventional silicon pressure transducers by almost three orders of magnitude.

The impact of swift heavy ions onto silicon oxide and silicon oxynitride on silicon creates etchable tracks in these insulators. After their etching and filling-up with highly resistive matter, these nanometric pores can be used as charge extraction or injection paths towards the conducting channel in the underlying silicon. In this way, a novel family of electronic structures has been realized. 1 The basic characteristics of these “TEMPOS” (=tunable electronic material with pores in oxide on silicon) structures are summarized. Their functionality is determined by the type of insulator, the etch track diameters and lengths, their areal densities, the type of conducting matter embedded therein, and of course by the underlying semiconductor and the contact geometry. Depending on the TEMPOS preparation recipe and working point, the structures may resemble gatable resistors, condensors, diodes, transistors, photocells, or sensors, and they are therefore rather universally applicable in electronics. TEMPOS structures are often sensitive to temperature, light, humidity and organic gases. Also light-emitting TEMPOS structures have been produced. About 37 TEMPOS-based circuits such as thermosensors, photosensors, humidity and alcohol sensors, amplifiers, frequency multipliers, amplitude modulators, oscillators, flip-flops and many others have already been designed and successfully tested. Sometimes TEMPOS-based circuits are more compact than conventional electronics.

To form C60/p-Si heterojunctions, thin fullerite films were evaporated onto silicon substrates. The fullerite conductivity is anisotropic with σL ≪ σT, where σL is the lateral, and σT is the transverse conductivity with respect to the fullerite layer geometry. As a consequence, the main current from one planar contact on the surface of the fullerite film to another does not flow through the fullerite layer, but through one p–n heterojunction into the underlying silicon layer, and from there via another p–n heterojunction to the second contact – even if the contact spacing is in the order of nanometers only. In this way, a novel family of varistors and/or transistors can be created. The basic characteristics of these structures named ‘FOS’ (fullerite on silicon) are shown and explained. The strong dependence of the lateral fullerite conductivity on ambient factors such as humidity and chemical environment makes the creation of sensors possible. The combination of two C60/p-Si heterojunctions towards n–p–n ...

The recent years have brought a renaissance of interest in ion tracks, for the sake of novel applications. This paper summarizes some of the newly emerging possibilities, and the strategies that have been initiated. Only a few applications that are based on latent tracks have emerged since then, such as the exploitation of phase transitions, chemical changes, the enhanced free volume along latent tracks, or their capability to trap diffusing penetrants. For contrast, etched tracks in both polymer foils and SiO2 layers appear to have a much greater application potential. Compact rods and tubules as well as dispersed nanosized matter can be embedded within the etched tracks to form the base of various applications. Some of them are summarized, and a few examples are described in detail.

In this study, the effects of electrical aging on emission stability of screen-printed carbon nanotube(CNT) emitter is investigated. Results show that stable and uniform emission currents from CNT emitter are obtained during the multiple field emission cycling. During the initial stage of electrical aging, an emission current fluctuation is observed and is gradually reduced and electron emission stabilized as time passes.

Instead of the CVD method to form a gate oxide layer, a wet-etching method was used to form an insulating layer and isolate cathode layer from gate electrode. The wet-etching process has many advantages such as simple manufacture process, mass production and low cost. A gate triode structure was fabricated because of its simplicity in fabrication process and beam broadening. A new type of triode structure using wet-etching process was made and their field emission characteristics, uniformity and efficiency for light source for backlight units(BLU) were investigated

In this report, we present field emission properties of the carbon nanotube (CNT) paste on cathode with a curved surface for MPA. The CNT paste was prepared using a mixture of multiwalled CNTs powders synthesized by chemical vapor deposition method, organic vehicles, and inorganic binders. We made use of both spin on glass (SOG) and a sensitizer as an inorganic binder and additive to the CNT paste. Then the paste was rubbed over a round cathode (diameter, D-4.3 mm) with a curved surface (a radius of curvature, R/spl sim/9.7 mm) designed specifically for our X-band (8-12 GHz) TWT-MPA.

We prepared carbon nanotube (CNT) pastes with different inorganic binders such as glass frit and spin on glass (SOG). MWNT powders grown by CVD were used for electron emissive source. The three-roll mill process was carried out for mixing and dispersion of CNT powders in organic vehicle as polymer matrix. CNT paste was printed onto various substrates such as an indium thin oxide (ITO) coated soda lime glass and a nickel plate. Then CNT paste was sintered under different ambient and temperature. For the analysis of the surface morphology of the cathode layer, field-emission scanning electron microscopy (FESEM) was used. The FE characteristics of CNT paste were measured in a high vacuum chamber with a parallel diode type configuration at 5/spl times/10/sup -6/ Torr. We obtained stable and high emission current from CNT paste with SOG. Our experiments have shown that CNT paste with SOG can use as efficient electron emitter in vacuum nanoelectronics such as radio frequency amplifier, field emission display and X-ray tube.

We have directly grown CNTs on the metal substrates by direct-current plasma-enhanced chemical-vapor deposition (DC-PECVD) using a gas mixture of C/sub 2/H/sub 2/ and NH/sub 3/ at relatively low temperature (550 /spl deg/C). In this study, we report field emission properties of CNTs depending on pattern sizes and spacings. Field-emission characteristic of CNTs was evaluated in a vacuum of 10/sup -6/ Torr in a parallel diode configuration. It is found that there is a correlation between pattern morphologies (such as window area, spacing, and dimension of window edge, etc.) and the field-emission properties. Furthermore, we found that the contact resistance between CNTs and substrate is a crucial factor for the saturation of field emission from CNTs.

Recent years have brought a renaissance of interest in swift heavy ion track technology, for the sake of prospective novel applications, i.e. creation of nanoscale electronic devices. This paper summarizes some of the newly emerging possibilities, and the strategies that have been initiated. Only a few applications that are based on latent tracks have emerged since then, such as the exploitation of phase transitions, chemical changes, the enhanced free volume along latent tracks, or their capability to trap diffusing penetrants. For contrast, etched tracks in both polymer foils and SiO/sub 2/ layers appear to have a much greater application potential. Compact rods and tubules as well as dispersed nanosized matter can be embedded within the etched tracks, to form the base of various applications.

The synthesis of films composed of fullerene and its compounds for use in sensor electronics is demonstrated to be promising. One can see from FESEM analysis that fullerite films have a polycrystalline columnar structure with column cross-section size about 100-300 nm and clear boundaries between the columns. C/sub 60/-Cu-J films have a high level of porosity and quite small resistance, which make them more convenient for application. Experiments confirm the possibility of using fullerite films in sensor electronics to produce humidity sensors. It is also possible to use the sensitivity of these films to isotropic pressure. Experiments with C/sub 60/-Cu-J films have shown quite strong dependence on the pressure of different sorts of gas medium, that could be used as gas-sensitive sensors.