Nanometer scale silicon tips are becoming increasingly important for use as field emitters. Applications include high resolution field emission displays and ultrahigh-speed devices. Of crucial importance is the precise control of tip shape and size if field emitters are to be used as microelectronic elements. This article reports on the fabrication procedure of silicon based gridded field emitter tips, using a new fabrication route which eliminates the need for an oxidation sharpening step.
X-ray technology provides a number of powerful tools used in many different areas of science and industry. The ability to focus x-rays is the key to a wide range of applications including medicine (diagnosis and therapy), industrial applications (lithography and inspection), astronomy (space telescopes) and x-ray imaging (microscopy and analysis). This work presents the design and microfabrication of a novel x-ray micro optical system for use in an x-ray microprobe for analysis of biological cells. A reflective micro-optical system capable of focusing a wide range of wavelengths is at an advanced stage of development. The lens system consists of a pair of microfabricated optical elements, one of which has variable curvature providing a unique mechanically-actuated zoom focusing capability. Experiments have been carried out to measure the changes of the focal length (lens curvature) and sensor calibration.
Using state of the art microfabrication techniques including high resolution electron beam lithography and plasma dry etching, uniform arrays of sharp polysilicon field emitters have been fabricated in gated configuration. Emission currents up to 2.5pA/tip have been obtained at 90 volts gate bias. Emitter life-time measurements have been carried out under ultra high vacuum conditions.
We report the fabrication and characterization of well-defined gated Si microtip arrays with diamond-like carbon (DLC) apexes. It was found that for a 40/spl times/40 gated Si tip array with DLC apexes, an emission current density up to 0.23 A/cm/sup 2/ can be obtained at an applied gate voltage of 200 V. The turn-on gate voltage of the devices is fall in a range of 38-50 V.
Theoretical and numerical treatments were devoted to the derivation of the threshold field for field electron emission from amorphous diamond thin films. Heavily doped n++-Si in the geometry of the tip was used as the cathode substrate. A three-step process involving internal emission, electron transport in the coating, and vacuum emission was employed to understand the emission. The derivation results predict that the potential barrier height at the Si-diamond interface is the main parameter that governs the threshold field for emission, which is consistent with the experimental phenomena that have been observed.
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