We have fabricated multiple-stacked Si quantum dots (QDs) with and without Ge core embedded in a SiO2 network on n-Si(100) and studied their field electron emission characteristics under DC bias application. For the case of pure Si-QD stacks with different dot-stack numbers, the average electric field in dot-stacked structures at which electron emission current appeared reached minimum value at a stack number of 11. This can be attributed to optimization of the electron emission due to enhanced electric field concentration in the upper layers of the dot-stacked structures and reduction of the electron injection current from the n-Si substrate, with an increased stack number. We also found that, by introducing Ge core into Si-QDs, the average electric field for the electron emission can be reduced below that from pure Si-QDs-stacked structures. This result implies that the electric field is more concentrated in the upper Si-QDs with Ge core layers due to deep potential well for holes in the Ge core.

Finely textured structures on a silicon surface were fabricated to act as field emitters via simple sandblasting using fine Al2O3 particles. Tests confirmed that the finely nicked structures function well as efficient field emitters. The emission current obeys the Fowler-Nordheim relationship, with a low electric field threshold. The fluctuation of the emission current was inversely proportional to the square root of the average emission current, and the long-term drift of the emission current was about 1% per hour at the average emission current of 108µA in the pressure range of 10-5Pa, indicating that the emitter offers a stable current output.

The effect of annealing on the field emission characteristics of a field emitter comprising diamond micropowder was investigated. The threshold voltage Vth at which the emission current begins to flow decreased as the annealing temperature increased, and a minimum Vth was obtained at an annealing temperature of 1345K. The reduction in threshold voltage was due to a reduction in the work function with annealing.

The field electron emission characteristics of a p-type Si emitter sharpened by a spirally scanned Ga focused-ion-beam milling process were investigated. Saturated Fowler--Nordheim (F--N) plots, which are unique phenomena of p-type semiconductor emitters, were observed. The slight increase of the emission current in the saturated F--N plots region was discussed in terms of the depletion layer width in which electron generation occurs. The temperature dependence of the field electron emission current was also discussed. The activation energy of carrier generation was determined to be 0.26,eV, ascribable to the surface states that accompany the defects introduced by the Ga ion beam. When the emitter was irradiated by a 650-nm-wavelength laser, the increase in the emission current, i.e., the photoexcited emission current, was observed in the saturated region of the F--N plots. The photoexcited emission current was proportional to the laser intensity.

To estimate the field emission current associated with an array of carbon nanowalls (CNWs), the model of the floating rods between anode and cathode plates was proposed. An approximate formula for the enhancement factor was derived, showing that the interwall distance of the CNW array critically affects the field emission. The field enhancement factor was almost one order of magnitude less than that of vertically aligned CNTs. Considering the field emission current density, the field emission can be optimized when the interwall distance is comparable with the wall height. For same separation distance, the macroscopic field strength of the CNW array is almost one order of magnitude higher than that of vertical CNT array to obtain the emission current of 1 mA from the cathode surface of 1 cm2.

A carbonaceous thin film was deposited on a tungsten single emitter by electrolysis of liquid methanol. The carbonaceous single emitter was thermally treated under vacuum conditions, and changes in its field emission characteristics were examined. The field emission characteristics obeyed the Fowler–Nordheim relationship for all annealing temperatures. The turn-on voltage decreased from 1640 V to 790 V with annealing up to 1373 K.

This work presents a novel field emission organic light emitting diode (FEOLED), in which an inorganic phosphor thin film is replaced by an organic EL light-emitting layer in the configuration of a field emission display (FED). The field emission electrons emitted from the carbon nanotubes (CNTs) cathode of the proposed FEOLED intensify the electron density in the multi-layer organic materials of the OLED; thus, resulting a higher luminous efficiency than that of a conventional OLED. Additionally, the luminance of the proposed FEOLED can be further increased from 10,820 cd/m2 to 27,393 cd/m2 by raising the current density of OLED through an external electron source. A balanced quantity of electrons and holes in the OLED, which is achieved by the proposed FEOLED increases the number of excitons and attributes the enhancement of luminous efficiency of the OLED. Under the same operating current density, the proposed FEOLED exhibits a higher luminous efficiency than that of a conventional OLED.

We report field emission from multilayered cathodes grown on silicon and glass substrates. The cathode consist of a layer of nanoseeded diamond and overlayers of nanocluster carbon (sp2 bonded carbon) and tetrahedral amorphous carbon (predominantly sp3 bonded carbon). These films exhibit good field emission characteristics with an electron emission current density of 1µA/cm2, at a field of 5.1V/µm. The multilayered cathodes on silicon substrates exhibit even lower emission threshold field of about 1-2V/µm for an emission current density of 1µA/cm2. The emission is influenced by the nanoseeded diamond size and concentration and the properties of the nano carbon over layer.

Field emission display (FED) is evolving as a promising technique of flat panel displays in the future. In this paper, various carbon based nanostructures are acted as cathode materials for field emission devices. Dendrite-like diamond-like carbon emitters, carbon nanotubes, carbon nanotips are synthesized by microwave plasma chemical vapor deposition. Many factors affect the performance of field emitters, such as the shape, work function and aspect ratio of emission materials. Modified process of carbon based nano-materials for enhancing field emission efficiency are included intrinsic and extrinsic process. These reformations contain the p-type and n-type doping, carburization and new ultra well-aligned carbon nano-materials. It is found that carbon nano-materials grown on micropatterned diode show higher efficiency of FED. In addition, to achieve a low- turn-on field, the novel scheme involving a new fabrication process of gated structure metal-insulator-semiconductor (MIS) diode by IC technology is also presented.

A type of carbon nanoform (carbon nanowalls: CNWs) has been successfully deposited on both Ni wafers and Ni wires using dc plasma chemical-vapor-deposition (CVD) method. Transmission electron microscopy (TEM) and Raman spectroscopy were used to characterize CNWs' microstructure. It is found that CNWs are well crystallized, and each CNW consists of several pieces of curved graphene sheets, presenting a quasi-two-dimensional geometry. The average length and width of CNWs are about 2-4µm, while their thickness is less than 7nm. Field emission measurement showed that such CNW films exhibited the excellent electron emission efficiency, comparable to the high-grade carbon nanotube (CNT) emitters. The threshold field defined as the field to obtained 1µA/cm2 is less than 1V/µm and the electrical field for 1mA/cm2 current density is only about 1.5V/µm. Moreover, the CNWs have stable emission behaviors, and we have successfully fabricated a kind of high-brightness lamps based on the CNW coated Ni wires.

Electron field emission from diamond, diamond-like carbon, carbon nanotubes and nano-structured carbon is compared. It is found that in all practical cases, emission occurs from regions of positive electron affinity with an emission barrier of 5eV, the work function, and with a large field enhancement. The field enhancement in nanotubes arises from their geometry. In diamond, the field enhancement occurs by depletion of grain boundary states. In diamond-like carbon we propose that it occurs by the presence of sp2-rich channels formed by the soft conditioning process.

For the realization of low-voltage full-color FEDs, requirements for phosphor for the FED are proposed. Especially, the influence of released gases or substances from phosphors on the field emission within the FED was made clear. It was clarified that the analysis of F-N plots of the V-I curve of field emission characteristics was helpful to know the interaction of field emission and phosphors. In the experiment, we first obtained the depth from the phosphor surface of the low voltage electron excitation in case of ZnGa2O4, where the region available for cathodoluminescence at the anode voltage of 400 V is about 63 nm deep from the surface. The characteristic of the 12.4 cm-320(trio)240 pixels low-voltage full-color FED is reported. The luminance of 154 cd/m2 was attained at the anode voltage of 400 V and the duty factor of 1/241. Supported by the high potential of the FED as a flat panel, each problem shall be steadily solved to secure the firm stand as a new full color flat display in new applications.