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Graphene–oxide–semiconductor (GOS) planar-type electron emission devices with a hexagonal boron nitride (h-BN) protective layer have demonstrated improved oxidation resistance while maintaining their emission performance. The devices with a monolayer or a multilayer (13 nm in thickness) h-BN protective layer can emit electrons even after oxygen plasma exposure (ashing). Remarkably, the device with a monolayer h-BN was able to emit electrons with a maximum efficiency of 11% after a 4-min ashing, showing that a thin h-BN protection layer can provide oxygen tolerance to GOS devices without a significant emission loss. The thicker multilayer h-BN imparted higher oxidation resistance to the device but with decreased emission efficiency compared with the device with monolayer h-BN. Thus, the use of h-BN necessitates a trade-off between the device’s emission performance and its oxidation resistance. In addition, the etching rate of h-BN by the oxygen plasma treatment was found to increase by exposure to air after the first plasma treatment, which indicates that the adherence of H2O to the surface of h-BN is one probable cause of h-BN etching during the ashing process.

A p-type graphene–oxide–semiconductor (GOS) planar-type electron emission device holds promise as a photocathode with a high quantum efficiency (QE) for generating a high-speed modulated electron beam. We report the electron emission properties of a planar-type electron emission device based on a GOS structure using lightly doped p-type silicon as a substrate under laser light irradiation. The electron emission efficiency is 12% with and without laser light irradiation. The emission current shows a four-order of magnitude enhancement in the high field region compared to that in the dark, and a 0.3% QE is obtained without a negative electron affinity surface. This GOS device exhibits advanced photoassisted electron emission characteristics with high photosensitivity on the order of mA/W. The photoemission from the p-type GOS device shows a fast photoresponse with a rise time of less than 0.2 µs, which is the same as that of the current amplifier. By contrast, it shows a slow response of about 2.4 µs at the fall time, which is determined by the diffusion process of the photoexcited electrons in the bulk. The use of a highly doped p-type silicon substrate can be a practical route for further improvement.

Objective Among standard treatments for infantile spasms, adrenocorticotropic hormone (ACTH) is reported as the best treatment, but ACTH is ineffective in one-half of the patients. To establish precision medicine, we examined pharmacoresistance of focal epileptic spasms (ES), generalized ES, and generalized ES combined with focal seizures, diagnosed based on the revised seizure classification of ILAE in 2017. Methods We conducted a retrospective nationwide study in Japan on the long-term seizure outcome of ES. Long-term seizure outcome was evaluated by seizure-free rate, seizure-free period, and Kaplan-Meier curve. Seizure-free was defined as seizure control for longer than two months. Results From the medical history of 501 patients, 325 patients had generalized ES only (GES group) at the start of the first treatment, 125 patients had generalized ES after focal seizure onset (FS-GES group), seven patients had focal ES after focal seizure onset (FS-FES group), and 24 patients had generalized ES combined with focal seizures after focal seizure onset (FS-GES+FS group). Seizure-free period of ES (generalized ES and focal ES) [mean (95% confidence interval)] was 2.7 (0.0-5.4) months in GES group, 1.1 (0.1-2.2) months in FS-GES group, 1.0 (0.2-1.9) months in FS-GES+FS group and 0.1 (-0.2-0.5) months in FS-FES group. Seizure-free rate, seizure-free period and Kaplan-Meier curve of generalized ES were almost the same in GES group and FS-GES group, with characteristics of superior response to ACTH. Mean seizure-free period of generalized ES combined with focal seizures was significantly shorter in FS-GES+FS group than in GES group. Mean seizure-free period of focal ES in FS-FES group was extremely short with exceedingly early relapse. Significance Pharmacoresistance was different in generalized ES, focal ES and generalized ES combined with focal seizures. ES with focal features or with focal seizures may have focal lesions, thus consider surgical options earlier in the course.

Highly efficient electron emission of 48.5% was demonstrated by a graphene/oxide/semiconductor (GOS) structure. The main factors contributing to this performance were investigated by analyzing the ...

In this work, a planar electron emission device based on a graphene/hexagonal boron nitride (h-BN)/n-Si heterostructure is fabricated to realize highly monochromatic electron emission from a flat surface. The h-BN layer is used as an insulating layer to suppress electron inelastic scattering within the planar electron emission device. The energy spread of the emission device using the h-BN insulating layer is 0.28 eV based on the full-width at half-maximum (FWHM), which is comparable to a conventional tungsten field emitter. The characteristic spectral shape of the electron energy distributions reflected the electron distribution in the conduction band of the n-Si substrate. The results indicate that the inelastic scattering of electrons at the insulating layer is drastically suppressed by the h-BN layer. Furthermore, the maximum emission current density reached 2.4 A/cm2, which is comparable to that of a conventional thermal cathode. Thus, the graphene/h-BN heterostructure is a promising material for planar electron emission devices to obtain a highly monochromatic electron beam and a high electron emission current density.

Spindt-type emitters were fabricated with cavities made of Al/Mo/SiO2 using the triode high power pulsed magnetron sputtering method. We explored the process parameters (gas pressure and voltage of the additional cap electrode) to optimize the sharpness of the emitter shape. We found that the intermediate pressure and voltage were suited to obtain sharp emitters. Further, we elucidated the crucial effect of the cavity dimensions, such as the cavity depth and hole diameter in the cavity ceiling, on the emitter shape. At a cavity depth of 480 nm, the aspect ratio (AR) of the emitter increased monotonously with an increase in the hole diameter. With a large hole diameter (900 nm) and even shallower cavity (380 nm depth), we attempted to reoptimize the process parameters. Consequently, a very sharp emitter cone structure with an AR exceeding 1.3 was obtained. The cap voltage that produced the optimum AR was found to decrease for the larger-hole and shallower-depth cavities. Finally, the applicability of the process for preparing a working emitter is discussed.

The planar type electron emission devices using atomic layered materials of graphene and hexagonal boron nitride (h-BN) were developed to suppress inelastic electron scattering within the device structure. High emission efficiency of more than 40 % and high emission current density of more than 100 mA/cm2 were achieved by the suppression of the inelastic electron scattering within the topmost gate electrode using graphene,. In addition, highly monochromatic electron emission with an energy spread of 0.18 eV in the full width at half maximum were realized by the suppression of the inelastic electron scattering within the topmost gate electrode and insulating layer using the graphene/h-BN heterostructure. These results would lead to several practical applications of planar type electron emission devices.

We propose the scanning electron microscope (SEM) using the graphene-oxide-semiconductor type planar electron emission device as an electron source. Graphene/Oxide/Semiconductor (GOS) structure realizes very high electron emission efficiency of over 30 % and it can be operated in low vacuum condition and low applied voltage. Therefore, SEM using the GOS electron source can eliminate several condenser lenses from the electron optics which are needed in the conventional SEM due to the very small divergence angle of the electron beams emitted from the flat surface. In this study, we installed the GOS type electron source into the conventional SEM and successfully obtained the stable SEM image with a probe current of 20 pA without noise using GOS electron source. In addition, we found the optimal electron optics for the parallel electron beams with a very small divergence angle of approximately 0 degree by the simulation of the electron beam trajectory.

A graphene-oxide-semiconductor (GOS) planar-type electron source is coated with a hexagonal boron nitride (h-BN) film to improve its oxidation resistance. The h-BN film is selected as a coating material owing to its high oxidation resistance and electron transmissivity. To evaluate oxygen resistance, the electron emission density versus applied gate voltage is measured before and after an atomic oxygen (AO) exposure for 4 minutes using an oxygen plasma asher. As a result, the device covered by h-BN emits electrons even after the AO exposure, indicating that the graphene electrode under the h-BN remains.

We report a case of saccharopinuria with hyperammonemia and hypercitrullinemia in a Japanese woman who presented with elderly-onset epilepsy, progressive cognitive decline, and gait ataxia. Blood amino acid analysis revealed an increase in citrulline, cystine, and lysine levels, and urine amino acid analysis showed increased citrulline and cystine levels. Urine metabolomics revealed an increased saccharopine level, leading to the definitive diagnosis of saccharopinuria. In western blots of liver biopsy samples, normal citrin levels were observed, suggesting that adult-onset citrullinemia type 2 (CTLN2) was not present. In addition, decreased argininosuccinate synthetase (ASS) levels were observed, and ASS1 gene, a causative gene for citrullinemia type 1 (CTLN1), was analyzed, but no gene mutations were found. Because the causes of hypercitrullinemia were not clear, it might be secondary to saccharopinuria. Muscle biopsy findings of the biceps brachii revealed diminished cytochrome c oxidase (COX) activity, mitochondrial abnormalities on electron microscopy and p62- positive structures in immunohistochemical analyses. Saccharopinuria is generally considered a benign metabolic variant, but our case showed elevated lysine and saccharopine levels causing ornithine circuit damage, mitochondrial dysfunction, and autophagy disorders. This may lead to so far unknown neurological disorders.

We previously reported highly monochromatic electron emission from the planar-type electron emission devices based on a graphene/hexagonal boron nitride (h-BN) heterostructure. In this paper, the electron energy distribution (EED) of these devices is examined to clarify the mechanism of monochromatic electron emission. We find that the monochromaticity of the electron beam depends significantly on the electronic structure of the substrate material; for the devices with an n-type silicon substrate, the narrowest FWHM of the electron beam is 0.18 eV, whereas that of devices with a metallic (Nb) substrate is 0.33 eV. At the same time, simulations considering the electron scattering by phonons acceptably reproduced the shape of each EED spectrum considering the small energy loss due to out-of-plane acoustic phonon modes in h-BN. Thus, the monochromatic electron emission from the $\mathrm{graphene}/h$-$\mathrm{BN}/n$-$\mathrm{Si}$ device is ascribed to a combination of the narrow energy distribution of electrons at the conduction band of the n-$\mathrm{Si}$ substrate and small phonon energy of the h-BN insulating layer. These features also realize the excellent emission properties in addition to the monochromaticity of the beam, such as a high emission current density of $9.3{\mathrm{A}/\mathrm{cm}}^{2}$, insensitivity to environmental pressure up to 10 Pa, and long lifetime of more than 7 days with little decay.

Electron emission properties of planar-type electron emission sources based on oxidized nanocrystalline silicon with graphene-gate electrode were investigated. The emission current was improved by an order of magnitude by vacuum annealing.

The digital type CMOS-MEMS cointegrated pressure sensor with a CMOS ring oscillator on a thin diaphragm was fabricated using cost-effective minimal-fab process and the successful operation of the fabricated pressure sensor was demonstrated, for the first time. It was confirmed that about 40 kHz difference in the oscillation frequency is observed in the fabricated CMOS-MEMS cointegrated pressure sensor chip by changing pressures from -40 to +40 kPa. This result is originated from the drain current variations of the longitudinal $ $ channel PMOSFETs of the CMOS ring oscillator owing to the piezoresistive effect. The developed CMOS-MEMS cointegrated pressure sensor is suitable for the application to the potable IoT sensor systems because it has a low-power consumption due to its all CMOS integration.

A graphene-oxide-semiconductor (GOS) planar-type electron source was fabricated by direct synthesis of graphene on an oxide layer via low-pressure chemical vapor deposition. It achieved a maximum electron emission efficiency of 32.1% by suppressing the electron inelastic scattering within the topmost gate electrode using a graphene electrode. In addition, an electron emission current density of 100 mA/cm^2 was observed at an electron emission efficiency of 16.2%. The electron energy spread was well fitted to Maxwell-Boltzmann distribution, which indicates that the emitted electrons are the thermally equilibrium state within the electron source. The full-width at half-maximum energy spread of the emitted electrons was approximately 1.1 eV. The electron emission efficiency did not deteriorate after more than 42 h of direct current operation. Thus, the GOS planar-type electron source has the potential to be an excellent electron gun for electron microscopy., This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in (https://aip.scitation.org/doi/10.1063/1.5091585) and may be found at [https://doi.org/10.1063/1.5091585].

In this study, we fabricated nano-capillary emitter arrays for stable ion emission of ionic liquid electrospray thrusters, employing the fabrication of field emitter arrays or gated nano electron sources. A nano-capillary emitter was successfully fabricated with a 100–300 nm capillary diameter, which prevented ionic liquid leakage by significantly increasing the fluidic impedance of the ionic liquid compared to a previously proposed emitter. An ion emission experiment was conducted with 1-ethyl-3-methylimidazolium dicyanamide as the propellant. Ion emission started at a low voltage of 61 V owing to a small gap of approximately 1 μm between the emitter and extractor electrode. The maximum current density was 43 mA cm−2 on the positive side and −13 mA cm−2 on the negative side without leakage of the ionic liquid, which was more than 100 times higher than that of conventional electrospray thrusters. Moreover, we obtained continuous ion emission without current intercepted by the extractor.

Summary Objectives Patients with primary immunodeficiency diseases (PID) are highly susceptible to various microorganisms. However, no population-based studies have been performed among common viral pathogens, such as respiratory syncytial virus (RSV), rotavirus (RV), varicella-zoster virus (VZV) and influenza virus (IV). The objective of this study was to reveal the clinical burden of these four infections among PID patients in Japan. Methods We conducted a nationwide survey by sending questionnaires to 898 hospitals with pediatric departments throughout Japan. Results Nine hundred ten PID patients from 621 hospitals were registered (response rate: 69.2%). Fifty-four of the patients were hospitalized due to these viral infections. The durations of hospitalization due to RSV and RV infections differed significantly in the PID patients with and without cellular immunodeficiency (12.0 vs 6.5 days, p = 0.041 ; and 14.0 vs 6.0 days, p = 0.031 , respectively). There was no significant difference in the duration of hospitalization in PID patients with and without cellular immunodeficiency who were hospitalized with IV infections (7.3 vs 6.1 days, p = 0.53). Conclusions Special attention should be paid to PID patients with compromised cellular immunity who present with RSV and RV infection due to their high risk for severe disease.

We have developed a highly sensitive, compact image sensor that comprises a field emitter array (FEA) and a high-gain avalanche-rushing amorphous photoconductor target, with the ultimate aim of developing an ultrahighly sensitive, compact, high-definition television camera. Double-gated FEs have an advantage of having a compact electron beam focusing system; however, image intensities reproduced by the sensor were nonuniform due to low electron beam current. Furthermore, the simulated electron beam current disagreed with the measured current. The electron beam current characteristics of two types of double-gated, Spindt-type FEs (both with improved electron beam current extraction) are discussed for possible use within the sensor: convex-structured and volcano-structured. A highly accurate simulation model of the image sensor using a double-gated, Spindt-type FE has been examined; the simulated electron beam currents extracted from the double-gated, Spindt-type FE are in agreement with the measured electron beam currents when the initial electron velocity is assumed, thus suggesting that the simulated anode current–anode voltage characteristic conforms to the measured one. For example, the electron beam currents extracted from the convex-structured and volcano-structured FEs when the focusing electrode is placed 0.2 $\mu \text{m}$ below the gate electrode opening at a focusing electrode voltage of 15 V are, respectively, 1.8 and 1.9 times larger than that extracted from the previously used FEs when the focusing electrode is stacked 1.5 $\mu \text{m}$ above the gate electrode. The results show potential for reducing the degradation of the uniformity of the reproduced image’s intensity, and show that the highly accurate simulation model of the sensor is valid to design the double-gated FEAs for the sensor.

The Minimal Fab concept was proposed in 2008 to produce low-volume customized devices with a low investment cost [1]. The different points of Minimal Fab compared with those of the conventional Mega Fab are as follows. (a) Wafer size is half-inch (12.5 mm), (b) the transferring and processing of the wafer are performed with a cleanliness level identical to that of a super clean room, and (c) the machine used compact dimensions of 144 cm height, 30 cm width, and 45 cm depth. Since the proposal of the Minimal Fab concept, many Minimal Fab machines and Minimal Fab processes have been developed actively for the fabrication of CMOS integrated circuits [2, 3]. However, the Minimal Fab process for MEMS sensor fabrications has not been developed sufficiently. In this work, we develop the CMOS-MEMS cointegrated process using the Minimal Fab deep-RIE and mask aligner. By using the developed process, we also fabricate and characterize the digital type CMOS-MEMS pressure sensor. The pressure sensing element in the CMOS-MEMS pressure sensor is the CMOS ring oscillator with the longitudinal PMOSFETs located at the edge areas of a thin circular diaphragm. In the device fabrication, we used (100) oriented half-inch SOI wafers, and the source-drain (SD) regions of the MOSFETs were patterned along with the direction to effectively utilize mechanical stress induced drain current variations. As the gate material, we used a 30-nm-thick PVD-TiN layer to obtain a suitable logic gate threshold voltage of the CMOS invertors. The circular diaphragm was fabricated using Minimal Fab mask aligner and deep-RIE. It was confirmed that the oscillation frequency changes from 360 to 400 kHz by changing pressures from -40 to +40 kPa in the fabricated CMOS-MEMS cointegrated pressure sensor chip. The developed CMOS-MEMS pressure sensor is suitable for the application to the battery drive IoT sensor systems owing to its low power consumption. [1] S. Hara et al., J. Jpn. Precis. Eng., vol. 77, no. 3, p. 249, 2011. [2] Y. X. Liu et al., Jpn. J. Appl. Phys. 56, p. 06GG01-1. [3] Y. X. Liu et al., J. Appl. Phys. 57, p. 06HD03-1.

Using a fabrication technology of field emitter arrays (FEAs), we have fabricated a high-density emitter array with 5-10 \mu m pitch as ion sources to improve the thrust density of electrospray thrusters. The emitter array is made on a Si wafer and consists of double Nb electrodes with sub-\mu m apertures, where ionic liquid as the propellant is expected to be extracted by applying voltage to the electrodes. This array can realize the emitter density of up to four million/cm2, which is four orders of magnitude higher than that of conventional electrospray thrusters.

We have proposed and developed a relatively low costed and simple constructed scanning electron microscope only with single objective lens but other convergent electron optics like condenser lenses using graphene-oxide-silicon planar type cold cathode (GOS) as an electron source. GOS has many superior aspects such as low voltage and low vacuum operation, stable emission, high emission current density, high efficiency against diode current, and so on. Especially, the quite low divergence of emitted electron beam from GOS have been expected to realize ideal parallel beam.

A prototype image sensor is developed using cadmium telluride-based photodiode and a volcano-structured FEA. Radiation tolerance of each component was tested by irradiating gamma-ray using cobalt-60 source. Gamma-ray tolerance of up to 1.2 MGy was confirmed for both FEA and photodiode.

Robustness of field emitter arrays (FEA) against high dose rate gamma-ray irradiation was confirmed. The current-voltage characteristics of the FEA were investigated in a vacuum vessel developed for in situ measurements under the irradiation. Although slight increase of the gate current was observed under the irradiation, the insulating layer kept the electrical insulation. As a result, FEA showed the almost identical current-voltage characteristics under the 1.3 kGy h-1 gamma-ray irradiation.

The Minimal Fab system is suitable for low-volume multi-product manufacturing because of its very low initial investment cost. We fabricated volcano-structured Spindt-type field emitter arrays that can be driven in matrix mode for image sensor application by using hybrid process of Minimal Fab system and conventional semiconductor fabrication system. We fabricated 0.6-$\mu \text{m}$-size gated field emitter by using Minimal Maskless lithography system. The planarization using Minimal CMP is performed to prevent break down between matrix type electrode.

The planar type electron emission devices based on a graphene-oxide-semiconductor (GOS) structure were developed. The GOS type electron emission devices fabricated by the combination of low temperature graphene deposition process of 800 $^{\circ\mathrm{C}}$ and the post device annealing at 300 $^{\circ\mathrm{C}}$ in vacuum achieved both of very high electron emission efficiency more than 10 % and high electron emission densities of around 100 mA/cm$^{\mathbf{2}}$

We developed an electron optical instrument for evaluating multi-emitters. This device enables us to evaluate both the percentage of active tips and the stability of the emission current from each active tip. Herein, we employed the instrument to observe a volcano-structured Spindt-type field emitter array (FEA) in the photoelectron emission microscopy (PEEM) and field electron emission microscopy (FEEM) modes. Furthermore, we measured the emission current from each active tip in the FEA. Consequently, we found that the number of active tips in the FEA can be considerably increased by aging at a relatively high voltage.

FDSOI MOSFETs and CMOS ring oscillators with different current flow directions were fabricated on ultrathin circular diaphragms using minimal-fab process, and their electrical characteristics were systematically investigated. It was found that the drain current of the channel MOSFETs and the oscillation frequency of CMOS ring oscillators are changed after diaphragm formation due to residual mechanical stress. This result is very useful for the digital type pressure sensor applications.

Methionine adenosyltransferase I/III (MAT I/III) deficiency is a metabolic disorder exhibiting persistent hypermethioninemia and neurological problems such as mental retardation and movement disorders by brain demyelination. Current diagnosis of MAT I/III deficiency completely depends upon newborn mass screening. Recently, correlation between the type of mutation of the MAT1A gene and clinical presentation has been investigated. The most common mutation, heterozygous for the autosomal dominant Arg264His mutation, is a relatively benign phenotype which requires no treatment. In contrast, care must be taken on the Arg292Cis mutation, especially if compounded with mutations at Arg356 (Arg356Pro, Arg356Leu, and Arg356Gln), for association of myelination disorder. Since MAT I/III catalyzes conversion of methionine to produce S-adenosylmethionine (SAM), supplementation of SAM is a therapeutic strategy to improve neurological problems. Hypermethioninemia can be corrected by methionine restriction; however, it may cause depletion of SAM. DNA testing is important for early diagnosis to prevent neurological manifestations.

Display Omitted The fabrication of the gated nano electron source is overviewed.Breakthrough in the gate formation process enables multi-gated FEA.Spindt-emitter fabrication is now further improved. Many kinds of attractive new applications, such as image sensors, stationary X-ray sources, and the column-less SEM, are investigated as post field emission displays that use a gated nano electron source. The fabrication of the gated nano electron source is overviewed from the conventional method to the latest one, especially in regarding to the gate formation process. Multi-stacked gate electrode formation using an etch-back method was developed recently, which is a very attractive method for generating a focused electron beam. The traditional Spindt-type emitter fabrication method is also being improved to the one that is easier and applicable to large area substrates. Using a double-layered photoresist as a lift-off layer and using HiPIMS sputtering instead of an e-beam evaporator was proposed. Thin film-type FEA fabrication is also improved to make vertically standing thin film by ion irradiation, which is applicable for making an emitter array on a large sized substrate.

Robustness of field emitter arrays against high-energy X-ray irradiation was demonstrated. The current-voltage characteristics of the field emitter array were investigated in a vacuum chamber connected to an electron accelerator. The electron beam with an energy of 1 MeV was incident onto a tungsten thin plate to produce X-rays. The field emitter array showed the almost identical current-voltage characteristics even under the X-ray irradiation, up to the absorbed dose of 1 kGy/h.

The sensitivity and specificity of a new rapid Mycoplasma pneumoniae antigen immunochromatography (IC) test, DK-MP-001, were determined using particle agglutination (PA) antibody response and loop-mediated isothermal amplification (LAMP) gene detection as the gold standard. Of 165 patients, 59 were diagnosed with M. pneumoniae infection based on a ≥fourfold rise of serum PA antibody during the course of the illness. Of the first visit swabs, 60 were positive for M. pneumoniae on LAMP, and 49 were positive for M. pneumoniae antigen on IC test. Compared with PA antibody and LAMP, the sensitivity/specificity of the IC test were 81.4% (48/59) and 99.1% (105/106); and 81.7% (49/60) and 100% (105/105), respectively. IC test detected antigen in pharyngeal swabs more sensitively than in nasal swabs for the same subjects (P

A planar-type electron emission device having a thin film diode structure such as a metal-oxide-semiconductor (MOS) [1] is a promising candidate as a fine electron source for applications of vacuum nanoelectronic devices, including environment-hard electronic devices, flat panel displays and high-sensitive image sensors. This is because the cathode operates at low extraction voltage and produces uniform and highly directional emission, compared with conventional field emitters with needle structure. Furthermore, the cathode is insensitive to the environment. However, the device is limited in emission current by its low efficiency (i.e., the ratio of the emission current to the total tunneling current) of typically less than 0.1 % due to strong scattering of hot electrons while traveling through the conduction band of both the oxide and the gate metal, after tunneling through the potential barrier in the oxide [2]. The reduction of the work function of the gate electrode by adsorption of alkali metals onto the surface [3] and the use of films containing nano- and micro-crystalline structure taking the place of the oxide layer have been proposed to improve the performance on the MOS cathode [4]. Another strategy is to reduce electron scattering within the topmost metal electrode by decreasing the electrode thickness [5-7]. In order to improve the emission efficiency and understand the emission mechanism we have fabricated the planar-type electron emission devices based on oxidized nanocrystalline Si (nc-Si) prepared by a pulsed laser ablation (PLA) technique and investigated their emission properties. The emission area of the device was designed 500 mm in diameter. The emission current and the efficiency are higher for thinner in the gate electrode, indicating tunneling is sensitive to the thickness of the gate. The electron emission efficiency is predicted to reach ~ 10 % if electron scattering on the inside of the topmost metal electrode is perfectly suppressed. In our presentation, we will discuss the detailed electron emission properties of the nc-Si based planar-type electron emission device. References [1] K. Yokoo et al., J. Vac. Sci. Technol. B 11, 429 (1993). [2] K. Yokoo et al., J. Vac. Sci. Technol. B 12, 801 (1994). [3] H. Mimura et al., APL 88, 123514 (2006). [4] H. Shimawaki et al., J. Vac. Sci. Technol. B 24, 971 (2006). [5] K. Yokoo et al., J. Vac. Sci. Technol. B 14, 2096 (1996). [6] H. Shimawaki et al., J. Vac. Sci. Technol. B 26, 864 (2008). [7] H. Shimawaki et al., J. Vac. Sci. Technol. B 28, C2C49 (2010).

To improve the thrust density of electrospray thrusters using ionic liquids as the propellant, we have fabricated a high-density emitter array utilizing the fabrication technique of a field emitter array (FEA) or gated nano electron sources. The density of the emitter array can reach approximately 4 million cm−2, which is four orders of magnitude higher than that of conventional electrospray thrusters. Performing deep reactive ion etching from the back side of the same structure as FEAs and removing their Ni cones by dilute nitric acid, we have successfully fabricated sub-μm scale capillary emitters with self-aligned extractor electrodes and ionic liquid reservoirs behind them. Current measurements were also conducted with EMI-BF4 and EMI-DCA as the propellant. Although the ion was not extracted with EMI-BF4 owing to its electrochemical reaction with the electrodes, both positive and negative ion currents were detected using EMI-DCA, where the current density exceeded that of conventional electrospray thrusters.

The PVD-TiN metal-gate SOI-CMOS integrated circuits including inverters and ring oscillators have successfully been fabricated on a half-inch (100)-oriented SOI wafer using the minimal-fab and mega-fab hybrid process, and their electrical characteristics have systematically been investigated. It was experimentally found that almost an ideal subthreshold slope (SS) of 67 mV/decade and an extremely low leakage current ( t |) for P- and N-channel devices due to the midgap work function of the PVD-TiN are obtained in the fabricated SOI-CMOS devices. Moreover, it was confirmed that the fabricated 41-stage ring oscillators show normal operations at different supply voltages and the oscillation frequencies are close to the estimated values by gate capacitances and drive currents. These excellent results indicate that the developed minimal-fab and mega-fab hybrid process is suitable for the fabrication of conventional CMOS integrated circuits.

Evaluation of the current density distribution of the electron beam emitted from the volcano-structured, double gated Spindt-type field emitter arrays were performed by numerical simulation in conjunction with analytical approach. By assuming the emitter shape as a part of a hyperboloid, the electric field near the emitter surface could be well estimated even by finite difference method. It was found that the gate height is important to maintain the current density.

A CdTe-based photoconductive target was designed for a radiation tolerant compact image sensor using field emitter array. Gamma-ray irradiation using 60Co showed that this target maintained its photoconductivity even after 1 MGy of gamma-ray irradiation.

Volcano-structured p-type silicon field emitter arrays have been fabricated by etch-back technique and investigated the photoresponse characteristics of electron emission excited by laser pulses. We have observed the current pulses from the device with the same response of the laser pulse.

Radiation tolerance of a field emitter array and a cadmium telluride-based photoconductor was investigated. The variation of the performance of these devices were investigated during the γ-ray irradiation by every 100–200 kGy. Total dose of irradiation reached 1.2 MGy, but no significant deterioration of the properties has been observed. A test tube exhibited successful photo-signal detection even after the irradiation of 1 MGy. As a result, it was found that the field emitter array and the photoconductor have sufficient radiation tolerance against γ-ray irradiation.

Electron emission properties of planar type electron emission device based on graphene-oxide-semiconductor (GOS) structure was investigated. The electron emission efficiency defined as the ratio of anode current to cathode current has no dependence on the graphene electrode thickness, which indicates that the electron scattering within the electrode is perfectly suppressed. A high electron emission current density of 1–100 mA/cm2 with high electron emission efficiency of 0.1–1.0 % was found to be achieved in GOS devices.