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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.

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.

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.

A vertical thin film field emitter array (VTF-FEA) was integrated with a thin film transistor (TFT) through a simple fabrication process that is compatible with the existing TFT manufacturing process. Specifically, the authors integrated a poly-Si TFT and a previously reported VTF-FEA. The VTF-FEA was fabricated using the ion-induced bending (IIB) technique. The IIB is a technique that can bend a cantilever by ion-beam irradiation and can be used with a wide range of materials. The emission from the TFT-VTF-FEA was controlled from subnanoampere to microampere levels using the built-in TFT. This work demonstrated that VTF-FEAs can be integrated with poly-Si TFTs and other electronic devices, such as metal-oxide semiconductor field effect transistors.

The authors proposed a simple fabrication technique of field emitter array based on a ion-induced bending (IIB) phenomenon. This technique is a very simple two-step process, involving the formation of a cantilever and subsequent ion irradiation. To form a vertical thin film emitter with practical ion dose, however, only a few specific film materials with limited thickness can be used. Therefore, an enhancement method of the IIB phenomenon is necessary. To enhance the IIB phenomenon, the authors proposed the double-layered film method. It was found that the ion-induced bending effect could be extremely enhanced by using a double-layered film method. The required dose could consequently be decreased to less than 5×1015cm−2 in the case of using a heavy element for the cantilever film. This methodology increases the potential of ion-induced bending as a simple fabrication technique for FEA device structures.

The authors describe a novel CdTe x-ray imaging device that is driven by an electron beam from a field-emitter array. This CdTe x-ray imaging device comprises a CdTe Schottky diode with a vertical thin-film field-emitter array (VTF-FEA). The VTF-FEA was fabricated by an ion-induced bending process and an etch-back technique. The output signal from the detector was obtained through the recombination of x-ray-generated holes and electrons emitted from the VTF-FEA. The output signal clearly depended on the intensity of the x-ray beam. The shape of a Cu plate was successfully detected by the VTF-FEA-driven CdTe diode.