E. I. Givargizov

Cathodoluminescent Field Emission Flat Panel Display Prototype Built Using Arrays of Diamond-Coated Silicon Tips

Vacuum-sealed field-emission non-addressable flat panel display prototypes are manufactured and tested. The single-color 50×45×3 mm displays with emissive area 17×17 mm use ungated diode configuration based on arrays of diamond-coated silicon tips. Brightness of 100–200 candelas per square meter is achieved at 1500 volts.

Controlled growth of filamentary crystals and fabrication of single-crystal whisker probes

The growth of filamentary crystals (whiskers) on a single-crystal substrate through the vapour-liquid-solid mechanism is described. The possibility of fabricating oriented systems of whiskers on the basis of this mechanism of crystal growth is noted. A phenomenon that is important for nanotechnology is noted: the existence of a critical diameter of whiskers, below which they are not formed. The phenomenon of radial periodic instability, which is characteristic of nanowhiskers, is described and the ways of its elimination are shown. The possibility of transforming whiskers into single-crystal tips and the growth of crystalline diamond particles at their apices are noted as important for practice. Possible applications of systems of whiskers and tips are described briefly. Particular attention is paid to the latest direction in whisker technology—fabrication of single-crystal whisker probes for atomic force microscopy.

Growth of diamond particles on sharpened Si tips

Growth of diamond particles on sharp silicon tips in a hot-filament CVD process was investigated. Highly preferential deposition of the particles on the ends of the tips has been found. An explanation is given for the phenomenon based on the idea that the ends have an increased temperature due to localized recombination of hydrogen, involved in the process, on the tips. HRTEM and electron diffraction investigations of the initial stages of the growth have demonstrated a direct localized epitaxial growth of diamond on silicon.

HREM of nanometric tips prepared from epitaxially grown silicon whiskers

Abstract Nanometric tips prepared from Si whiskers frown epitaxially by VLS techniques were investigated by HREM. Whiskers were grown on 0.23 × 2mm (111)Si ‘butt-ends’ of plate-shaped substrates oriented in using X-ray diffraction techniques. Since the tip ends are suitably thin, and in an appropriate orientation— —for lattice imaging, the HREM images which are obtained display facetting at the end of the tips. SEM images of the bases of tips removed mechanically from the substrate, and also two-beam diffraction contrast TEM images show that the cross-sections of the nanometric tips prepared by a one-stage process are equilateral triangles with truncated corners. This is also confirmed by observing changes in the lattice image contrast across tips, with the appearance of characteristic half-spacing contrast at specific thicknesses typical of wedge-shaped crystals. According to HREM, the lattice is defect-free. There are two versions of tip etching (two combinations of three [111] shape-making faces). The extreme ends of the tips are atomically sharp, with an apex cone angle of 18–24°. Tips prepared by a two-stage process are characterised by a thick base and thin ‘cylindrical’, needle-shaped part 50–200 nm in diameter and 6–20 μm long. The angle which forms the needle profile of the thin part with [ 1 ¯ 11 ] growth direction is 1.5–4°. Profile imaging of the thin part reveals small steps along [111]. The ends of these tips are also atomically sharp, and resemble those prepared by a one-step etching process.

Nucleation and growth of crystalline diamond particles on silicon tips

The data on the deposition, structure, and electric properties of crystalline diamond particles at silicon tips grown on single-crystal silicon substrates obtained over the last decade, mainly at the Institute of Crystallography of the Russian Academy of Sciences, have been reviewed. It is shown that silicon emitters coated with crystalline diamond are highly electrically stable. They are used to prepare long-life cathodoluminescence light sources.

Investigation of the formation of nanowires from silicon whiskers

Nanowires have been prepared by the high-temperature oxidation of Si whiskers. The dependences of the nanowire formation on the oxidation parameters have been investigated. The oxidation rate is shown to depend on the whisker diameter. Oxidation in dry oxygen at temperatures no higher than 950°C results in self-stopping; i.e., the nanowire diameter is stabilized. Stabilization is not observed at oxidation temperatures above 950°C or at oxidation in wet oxygen. Oxidation at higher temperatures made it possible to obtain nanowires ≤5 nm in diameter in relatively thick (up to 200 nm in diameter) whiskers.

Specialized whisker probes for nanodiagnostics

A short review of specialized probes for nanodiagnostics with an accent to using for this aim of silicon whisker tip probes prepared by crystal growing from vapor phase. The probes ensure significant advantages in comparison with the standard probes that are produced by etching single-crystalline silicon wafers. Whisker probes for chemical force microscopy and for biological force microscopy are considered; their development for new versions, “single-molecule force microscopy” has been noted. Possibilities of the whisker probes for magnetic force microscopy and its new version, so-called “nano cluster magnetic force microscopy” that can be useful at chemical design on nanosized high-spin molecules are analyzed. Possibilities of the whisker probes for improvement of resolution and sensitivity of the capacity force microscopy for investigations in impurity distribution in semiconductor crystals and films are considered.

A Cathodoluminescent Screen of Columnar Structure for Field Emission Displays

We have suggested and implemented a method of creation (growing) of sublimate‐screens formed by single‐crystal luminophor columns which are perpendicular to an amorphous (e.g., glass) substrate. The diameters of the columns are 3–5 μm, the height 7–10 μm. The columnar single‐crystal structure of the screen ensures the high light yield and radiation color needed for field emission displays. It is possible to select the growing regime so that the columns are very closely spaced (1–2 μm). The gaps can be filled with a conducting opaque material that increases the contrast of the screen and improves their electrical conductivity.

Phosphor screens with columnar structures for field emission displays and other applications

A new design for thin-film phosphors screens is proposed, and its realization is demonstrated. The design consists in single-crystalline columns of the phosphor material. The columns are across the screen approximately perpendicular to it. Formation of the design is ensured by an action of isolated particles of catalysts deposited onto a substrate. The columns act as light-guides and, in such a way, ensure high resolution, high efficiency, and high stability of the screens.

Diamond Particles on Silicon Tips: Preparation, Structure, and Field Emission Properties

Negative electron affinity (NEA) of diamond as a property inherent in the material is known for a time [1]. Quite recently, the property has attracted a strong interest for applications in vacuum microelectronics and in other fields of modern science and technology [2]. Tentative applications in field-emission displays (FED) is probably one of the most popular.