Silicon Microtips Research Articles

Surface application of metal silicides for improved electrical properties of field-emitter arrays

This paper concerns the positive effects of chromium or titanium silicide coating on the electrical characteristics of micro-tips. The metal-coated silicon micro-tips were prepared by the silicidation process. The surface morphologies and electrical properties of the samples were measured and analyzed. It was found that the application of chromium silicide to silicon field emitters decreases the current fluctuation range to about 50% that of a pure silicon emitter. Both metal-silicide-coated samples exhibited high discharge resistances. In particular, the titanium-silicide-coated sample exhibited a discharge resistance up to an emission current of , which is higher than that of the chromium-silicide-coated sample. A silicon-metal-silicide vacuum-band model is proposed to explain the electrical characteristics. The effect of stabilization can be explained in terms of reduced number of chemically active sites resulting in a silicide-protected and chemically stable layer, hence the higher electrical conductivity of the material.

Beam focusing characteristics of silicon microtips with an in-plane lens

Single microtips, 2/spl times/2 and 10/spl times/10 arrays of microtips surrounded by an integrated focusing ring, were fabricated and their focusing characteristics experimentally investigated. Observation of the beam on a phosphor screen shows that the focusing is very effective for single microtips and 2/spl times/2 arrays; moreover, the reduction in emitted current is much smaller than for double-gate focusing. 10/spl times/10 arrays of microtips, however, do not generate very focused beams. These results agree well with simulations. The possibility of simultaneous focusing and deflecting is also discussed, and a new structure combining the advantages of double-gate and surrounding ring focusing is suggested.

Fabrication of high aspect ratio silicon micro-tips for field emission devices

The evolution of higher order {221} and {331} crystal planes during corner undercutting in the anisotropic etching of (100) silicon is discussed, and the occurrence of highly vertical (72.5°) {311} planes unique to KOH etches are demonstrated. Using a combined etching technique, very high aspect ratio micro-tips are formed and their distinct advantages for vacuum microelectronics and field-emission devices (FED) are described.

Chemical vapor deposition and plasma-enhanced chemical vapor deposition carbonization of silicon microtips *

Silicon microtips for field emission applications were coated with thin silicon carbide layers by chemical vapor deposition (CVD) and plasma-enhanced CVD (PECVD) at temperatures of 800 to 1200 °C using propane or a methane/propane mixture as carbon sources. Coatings from 4 to 30 nm thick were obtained. Scanning electron microscopy and Auger electron spectroscopy were used to investigate the morphology and composition of the carbonized tips. Both silicon carbide and pure carbon coatings could be formed depending on the process parameters used. Sharp carbonized tips were obtained by PECVD using propane flow concentrations.