A.N. Stepanova

Growth of diamond particles on sharpened silicon tips for field emission

Abstract Preparation and field-emission characteristics of silicon tips coated by diamond particles are described. The particles grew by a hot-filament CVD process preferentially on the very ends of the tips. An explanation is given for the preferential deposition based on the idea that the real temperature of the ends is markedly, about 200 °C, greater than the average temperature of the tips. Field-emission measurements showed that diamond-coated silicon tips can give currents as large as 500 μA before they are destroyed, at least one order of magnitude larger than uncoated silicon tips. The temporal stability of the emission current was high.

Ultrasharp diamond-coated silicon tips for scanning-probe devices

The goal of the work was to develop a technique for preparing cantilevers for atomic force microscopy with ultra-sharp, ultra-hard tips. For this purpose, two technologies were combined: (a) preparation of Si cantilevers with the principal (111)-oriented face; (b) formation of the probe by growing of single-crystal Si columns on the cantilevers from the vapor phase (vapor-liquid-solid VLS) with subsequent sharpening, deposition of diamond on the tips formed, and sharpening of the diamond tips by ion-beam bombardment. Sharp diamond tips with curvature radii as small as 20 nm were formed.

Heteroepitaxial deposition of single-crystal diamond particles on sharpened Si tips

Abstract Heteroepitaxial single-crystal diamond particles were formed on sharpened Si tips in a hot-filament CVD process at increased content of atomic hydrogen in the vapor phase.

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.

Preparation of Ultrasharp Diamond Tip Emitters by Ion Beam Etching

Ion-beam milling was used for sharpening of diamond particles on ends of silicon tips. The sharpened diamond samples were used as Jield-electron emitters. IV characteristics of the emitters were measured. An effect of conditioning of the emitters was observed: after an emitter worked at least during several hours, its current increased for several orders of magnitude and became stabilized.

Field-Emission Lamps Based on Diamond Coated Silicon Emitters

Diode-type field-emission flat lamps based on silicon field emission arrays with diamond coatings were fabricated. The bri htness of the flat light source with green phosphor was estimated to be about 2000 cd/m at voltage of 3 kl? The lamps of dgferent colors were fabricated: green, red and white. The life time measurements have been performed during 1200 hours. Effects of density of emitters in array and resistivity of silicon substrate on the ungormi9 of emission was studied. B

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.