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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.

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.

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].

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.

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.

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.

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.

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.

The electron emission properties of planar-type electron emission devices based on a graphene-oxide-semiconductor (GOS) structure before and after vacuum annealing were investigated. The fluctuation of the electron emission current was around 0.07%, which is excellent stability compared to the conventional field emitter array. The GOS devices were operable in very low vacuum of 10 Pa without any deterioration of their electron emission properties. Improvement of the electron emission properties of the GOS devices was achieved by vacuum annealing at 300 °C. The electron emission efficiency of the GOS type electron emission devices reached 2.7% from 0.2% after vacuum annealing. The work function of the graphene electrode was found to decrease 0.26 eV after vacuum annealing by Kelvin force probe microscopy analysis. These results indicated that the improvement of the electron emission efficiency of the GOS devices by vacuum annealing is due to the decrease in the work function of the graphene electrode.

Electron-emission properties of silicon field-emitter arrays treated with trifluoromethane plasma (Si:C-FEA) were evaluated under H2, CH4, CO, CO2, O2, and C2H4 ambients. Oxidizing gases, including O2 and CO2, make shortened the lifetime. However, reductive gases such as H2 and CH4 lengthened the lifetime longer. On the other hand, C2H4 caused a decrease of the emission current, despite the fact that C2H4 is considered to be one of the reductive gases. Furthermore, emission properties can be recovered by the aging process in an ultrahigh vacuum. This is probably attributable to physisorption and desorption of C2H4 molecules or decomposed molecules onto the emitter surface of the Si:C-FEA.

The electrostatic-focusing Spindt-type field emitter array (FEA) pitch was optimized for an FEA-high-gain avalanche rushing amorphous photoconductor (HARP) image sensor. Simulation results showed that a narrow FEA pitch of less than 2.2 µm deteriorates the electrostatic focusing effect.

Photoassisted electron emission from p-type silicon field emitter array with sub-micron gate aperture under illumination of blue laser pulses is investigated. The FEA device is designed to minimize the photogeneration of slow electrons outside the depletion layer. We present the optical response studies of the device by laser pulses.

A research project on the development of radiation tolerant compact image sensor with a field emitter array started in 2013. The purpose of the project is to develop key components of the image sensor that has sufficiently high radiation tolerance, as a step to investigate the interior of the nuclear reactor of Nuclear Power Plant Fukushima the 1st. A volcano-structured double-gated Spindt-type field emitter array is now under development. As a photoconductor, a layer of cadmium telluride and cadmium sulfide is adopted. Fundamental characteristics of the image sensor with these components together with the radiation tolerance are examined.

We propose use of silicon field emission array as a novel charge neutralization device for ion implanter. Fundamental characteristics of the emitted electrons, i.e. energy distribution and operation in high vacuum were investigated. As a result, energy spread was narrow enough but unexpected energy peak shift was observed. To reduce the energy spread and peak shift, a FEA with less number of tips and with narrower gate diameter is necessary. The FEA could be operated about 100 h in high vacuum.

Silicon nanowires with programmable conductivity which utilized sensitivity of conductance to surface charging have been investigated in terms of complementary operation of p- and n-type devices. The device fabricated from a silicon-on-insulator (SOI) wafer consists of a nanowire (width ≈ 30 nm) and side gates for control of surface charging onto the nanowire. The wire current clearly exhibited hysteresis by sweeping the side gate voltage at a constant rate. The transistor characteristics obtained using the SOI substrate as a back gate also exhibited programmable threshold voltage by applying a pulse bias to the side gate. Surface potential imaging of the nanowire by means of scanning Maxwell-stress microscopy (SMM) has been carried out for correlating the programmability to surface charging. The SMM images clearly explained the origin of the programmability and the complementary operation of the p- and n-type nanowires.

Vacuum microelectronics is potential technology of building novel electronic devices that cannot be realized by using solid-state electronics. This paper reviews the current status of this technology. Micron-size cold cathodes using field electron emission have been developed for the electron sources of novel vacuum electron devices. Recently field emission displays are getting into the flat panel display market.

Field emission from individual tips in n- and p-type silicon field emitter arrays (FEAs) has been directly evaluated by using an electrostatic lens projector. The number of the emission spots in the p-type FEA increased with increasing total emission current, and the p-type FEA exhibited better uniformity of the emission than the n-type FEA. In order to improve the emission uniformity, the operation of the FEAs under an atmosphere of ambient gas was executed. The emission uniformity was improved dramatically by exposing C2H4 gas. Also, surface modification of Si field emitters was investigated for damageless vacuum sealing. The vacuum sealing process reduced the emission currents from the nontreated Si FEA by a factor of 10. On the contrary, the emission current from the CHF3-plasma-treated FEA did not change before and after the vacuum sealing process.

Solid source diffusions of phosphorus (P) and boron (B) into the half-inch (12.5 mm) minimal silicon (Si) wafers by spin on dopants (SOD) have been systematically investigated and the physical-vapor-deposited (PVD) titanium nitride (TiN) metal gate minimal silicon-on-insulator (SOI) complementary metal–oxide–semiconductor (CMOS) field-effect transistors (FETs) have successfully been fabricated using the developed SOD thermal diffusion technique. It was experimentally confirmed that a low temperature oxidation (LTO) process which depresses a boron silicide layer formation is effective way to remove boron-glass in a diluted hydrofluoric acid (DHF) solution. It was also found that top Si layer thickness of SOI wafers is reduced in the SOD thermal diffusion process because of its consumption by thermal oxidation owing to the oxygen atoms included in SOD films, which should be carefully considered in the ultrathin SOI device fabrication. Moreover, normal operations of the fabricated minimal PVD-TiN metal gate SOI-CMOS inverters, static random access memory (SRAM) cells and ring oscillators have been demonstrated. These circuit level results indicate that no remarkable particles and interface traps were introduced onto the minimal wafers during the device fabrication, and the developed solid source diffusion by SOD is useful for the fabrication of functional logic gate minimal SOI-CMOS integrated circuits.

In this study, an array of Mo cones for volcano-structured Spindt-type microelectron emitters were fabricated. A recently developed triode high power pulsed magnetron sputtering system was used to control the positive plasma potential and efficiently accelerate ion species. By applying a proper positive voltage to the additional electrode, the authors obtained good cone shapes with high aspect ratios in a water-cooled microcavity structure made of two resist layers, which was previously impossible by conventional vacuum evaporation techniques. The effects of ion acceleration on the alignment of ions along the normal direction, as well as on the stress in the deposited film, are discussed. The former is important for the formation of sharp cones, while the latter is crucial for achieving stable fabrication.

A new fabrication method of Spindt-type field emitters will be presented. In our method, double-layered photoresist is used as a lift-off layer for making an emitter tip. The selection of the emitter material is a key for this process. We selected Ni as the emitter material. We also apply volcano-structured double-gate for the Ni Spindt-type FEA.

We have studied the photoassisted electron emission from a p-type silicon field emitter array under illumination of laser lights with 633 nm and 405 nm wavelengths. The increase of the emission current under light illumination is proportional to the emission current in the dark. The significant influence of the polarization in photoassisted emission for each wavelength was not observed.

We have fabricated a gated niobium nitride field emitter by the transfer mold method. A silicon mold was fabricated by anisotropical etching, followed by oxidation of the mold and deposition of niobium nitride. Niobium nitride thin films were prepared by ion-beam-assisted deposition. After attaching the sample to a glass substrate, the silicon mold was removed by mechanical and wet etching. A molybdenum thin film was then deposited by electron-beam evaporation. Formation of a gate aperture and an insulating silicon dioxide layer were performed by wet etching of only the apex, with other regions being protected by a photoresist layer. An electron emission test of the fabricated emitter array was performed in a high vacuum. We confirmed electron emission of up to 0.1 μA at the emitter–gate voltage of 30 V.

We report optically modulated electron emission from gated p-type silicon field emitter arrays (Si-FEAs). The device's “volcano” structure is designed to control the photoexcitation of electrons by transmitting light through the small gate aperture, thereby minimizing the photogeneration of slow diffusion carriers outside the depletion region in the tip. Compared to that in the dark, the emission current was enhanced by more than three orders of magnitude in the high field region when irradiated with blue laser pulses. Results from the time-resolved measurements of photoassisted electron emission showed that these possess the same response as the laser pulse with no discernible delay. These results indicate that the volcano device structure is effective at eliminating the generation of diffusion carriers and that a fully optimized FEA is promising as a photocathode for producing high-speed modulated electron beams.

The electric field required to emit electrons for boron-doped diamond together with the emission site was estimated using measurement systems that can precisely control the emitter–collector gap and lateral position. Three different types of field emitters were prepared by microwave plasma chemical vapor deposition. Type A was a typical diamond film on a flat silicon substrate, type B was a heteroepitaxial diamond film that was deposited on a (111) oriented platinum substrate, and type C was a pyramidal diamond film fabricated by the transfer mold method. For all the emitters, the voltage required to extract 0.2 nA was measured as a function of the emitter–collector gap, where the device of the emitter–collector configuration is approximated by a pair of parallel plates. The results showed that a strong electric field was applied in front of the emitter. For type B, the emission current distribution was measured by a device in which the collector was an etched needle. It was found that the emission curren...

We fabricated Spindt-type field emitters with four kinds of cathode material (Au, Ni, Pt, and Mo) and estimated the emission characteristics. The Pt emitter showed the best emission characteristics with the lowest operating voltage and the most stable emission among the four kinds of emitters. The difference of the operating voltage among the cathode material is attributed to the emitter shape. The reason the Pt emitter showed stable emission is its inert surface. Pt is a promising material for Spindt-type field emitters from the cone shape, melting point, and inert surface.

We have deposited niobium nitride thin films by ion beam assisted deposition and evaluated their properties from the viewpoint of a cathode material for vacuum microelectronics devices. Substrate temperature and ion–atom arrival rate ratio were selected as deposition parameters. The film properties of nitrogen composition, crystallinity, electric resistivity, work function and sputtering yield against a low-energy argon ion bombardment were investigated. It was found that polycrystalline films could be obtained at the substrate temperature higher than 500°C, and the composition could be controlled by the ion–atom arrival rate ratio. The results also showed that the stoichiometric nitride film exhibited superior properties of a lower work function and a lower partial sputtering yield of niobium. The electron emission test also demonstrated a lower current fluctuation for the stoichiometric films. In summary, ion beam assisted deposition provided a low temperature process which could control the film properties suitable to a cathode material.

The authors have developed a highly sensitive, compact image sensor comprising a field emitter array (FEA) and a high-gain avalanche rushing amorphous photoconductor (HARP) target with the ultimate aim of developing an ultrahigh sensitivity, compact, high-definition television camera. Double-gated field emitters have the advantage of a compact electron beam focusing system; however, image intensities reproduced by a sensor with the double-gated, Spindt-type field emitter array with the focusing electrode stacked 1.5 μm above the gate electrode were nonuniform owing to low electron beam current. The minimum required electron beam current extracted from the double-gated field emitter array is considered for possible use with the sensor. Furthermore, a suitable field emitter array pitch to balance the electron beam current and the electrostatic-focusing lens strength was simulated. For the sensor's design guidelines, a field emitter array pitch of approximately 3 μm would be reasonable in the case of employing the volcano-structured, double-gated, Spindt-type field emitter array with the focusing electrode placed 0.2 μm below the gate electrode hole. Based on simulation results, an image sensor with the volcano-structured, Spindt-type, 3.1-μm-pitch FEA with the focusing electrode placed 0.2 μm below the gate electrode hole was fabricated. It was confirmed that the minimum electron beam current extracted from the volcano-structured FEA was approximately 2 μA/pix, and the sensor could obtain images with improved image intensity uniformity by utilizing the electrostatic-focusing effect. These results indicate that the volcano-structured, double-gated, Spindt-type FEA is potentially suitable for high-definition television FEA-HARP image sensors.

Graphene was used as the topmost electrode for a metal-oxide-semiconductor planar-type electron emission device. With several various layers, graphene as a gate electrode on the thin oxide layer was directly deposited by gallium vapor-assisted chemical vapor deposition. The maximum efficiency of the electron emission, defined as the ratio of anode current to cathode current, showed no dependency on electrode thickness in the range from 1.8 nm to 7.0 nm, indicating that electron scattering on the inside of the graphene electrode is practically suppressed. In addition, a high emission current density of 1–100 mA/cm2 was obtained while maintaining a relatively high electron emission efficiency of 0.1%–1.0%. The graphene-oxide-semiconductor planar-type electron emission device has great potential to achieve both high electron emission efficiency and high electron emission current density in practical applications.

It was found that the etch rate of Si in tetramethylammonium hydroxide (TMAH) solution is significantly retarded by introducing ion implantation damage. By utilizing this new phenomenon, i.e., ion-bombardment-retarded etching (IBRE) of Si, a novel process to fabricate an ultrathin Si channel wall for the vertical double-gate (DG) metal-oxide-semiconductor field-effect transistor (MOSFET) was developed. We succeeded in fabricating a vertical Si wall with thickness of 16 nm on bulk Si substrate with no introduction of dry etching damage. The effectiveness of thinning the Si channel wall to the characteristics of a vertical DG MOSFET was examined by means of simulations.

We propose Spindt-type field emitter array fabrication process using the high power impulse magnetron sputtering (HiPIMS) deposition. HiPIMS method can get a lot of ionized sputtering particles due to high plasma density. We think that highly collimated film deposition may be realized by combining the potential control of the sputtering target and HiPIMS method. We tried that molybdenum deposition in a gatehole structure using potential-controlled HiPIMS method. And, we demonstrated that the possibility of the FEA fabrication process using this method.

We have proposed field-emitter-array fabrication process based on thin-film processes, to fabricate FEA having high compatibility with metal-oxide semiconductor field-effect-transistor and thin film transistor processes. This proposed process was realized using ion-induced bending technique, which can bend thin-film cantilevers to form high aspect ratio structure array. The field electron emission of more than 1 A/cm3 was obtained from our fabricated FEA.