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We are developing volcano-structured double-gate Spindt-type field emitter array (VDGS-FEA) that is applicable for image sensors. The FEA have good focusing characteristics without current degradation under the beam focusing condition. In this paper, we will present detailed fabrication and typical emission characteristics of VDGS-FEA.
Energies of emitted electrons from n-type diamond NEA surface and graphene/n-type diamond junction were measured by combined field emission spectroscopy/ultraviolet photoelectrons spectroscopy (FES/UPS) system. For n-type diamond NEA surface, the energies of emitted electrons indicated that the electrons emitted from conduction band of the diamond. For graphene/diamond junction, electron emission...
We report field emission properties of gated p-type silicon field emitter arrays with submicron gate aperture induced by laser pulses. Polarization dependent photoemission is observed and the current shows linear dependence on laser power. The results indicate that the current pulses from our devices are created by photo-field emission process dominantly.
In this study, amorphous selenium based photoconductor with different film thicknesses were fabricated and applied to prototype photodetectors. The use of thick photoconductor resulted in higher sensitivity due to carrier multiplication. Advantages and disadvantages of the thick photoconductor were investigated.
High brightness and stable cathode has been required for SEM use. We have been studied about Tungsten Carbide (WC) field emission cathode to achieve low-cost and easy to use, high brightness cathode. Tungsten carbide layer is formed on W-FE tip by heating in Ethylene(C2H4) gas. This WC field emission cathode indicated low work function.
We have studied Smith Purcell radiation (SPR) as the one of solutions to emit high frequency electro magnetic wave. The SPR is a kind of mechanism of spontaneous emission, which consists of an accelerated electron beam and interaction metal circuit. Spontaneous emission emits from electric dipole in SPR and the output power is very weak. In order to increase radiation power, using short pulse is one...
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...
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.
Permeation of low-energy electrons through graphene was investigated. A multi-layered graphene was transferred on a Cu mesh, and electron beam was scanned over the mesh and the graphene. Up to 1% of the incident electron beam permeated through the graphene at landing energy of 20 eV. The result suggested a possibility of graphene to be used as a window material for scanning electron microscopy and...
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.
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...
NEA GaAs photocathodes with high quantum efficiency (QE) and high response speed are expected as a electron source for THz frequency vacuum devices. To achieve high QE and high response speed, further understanding of the electron emission mechanism is necessary. This study focused on the formation process of NEA surface on a GaAs photocathode. The results suggests that NEA surface allows the electron...
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.
Volcano-structured double-gate Spindt type field emitter arrays were fabricated using double-layered photoresist as a lift-off layer for the image sensor application. The emitter material that we tested is Ni and Mo/Ni. Electron beam focusing characteristics were evaluated by scanning slit method.
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 two type of graphite field emission cathodes: graphite nanospines (GNS) and graphite field emitters inflamed at high temperatures (GFEIHT) and applied for X-ray tubes using these cathodes. The morphologies and structures of the two cathodes were quite different. However, these emitters have excellent field emission characteristics. Raman spectroscopy indicated that GFEIHT consisted...
To improve QE of the photocathode using surface plasmon resonance, we have employed the new arrangement of the photocathode and incident light, where the direction of the surface plasmon coincides with the momentum direction of the emitting electrons. We have achieved the QE by 103 times larger than that of the conventional photocathode using surface plasmon resonance.
In this study, an attempt was made to reduce dark current of amorphous-selenium (a-Se) based photodetector. An electro-chemical method was utilized to incorporate chlorine (Cl) into a-Se, in order to form a blocking junction within a-Se film. Current versus applied voltage characteristic of Cl-incorporated film showed a rectifying characteristic, which, when combined in a photodetector, should reduce...
Graphene/hexagonal boron nitride (h-BN) was characterized. Field emission from graphene/h-BN/Si structure showed low threshold voltage and enhanced emission current. Fowler-Nordheim (F-N) plots were applied to discuss the obtained field emission properties. We also examined work function using ultraviolet photoelectron spectroscopy (UPS). The obtained data suggested that graphene modified work function...
To investigate mechanisms of the polarization phenomena in the CdTe radiation detectors, we used optical laser pulses for carrier generation and detected the electrical response from the CdTe detectors as a function of carrier-generation position in the detector. Temporal change of the internal electric field at defined position in the CdTe detector can be directly observed by the laser pulse measurements...
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