Control of Particle Size and Position of Nano-crystalline Silicon

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Recent progress in the fabrication technology of silicon nanostructures has made possible observations of electronic transport phenomena characteristic of silicon quantum dots, such as single electron tunneling, ballistic transport, visible photoluminescence and electron emission. Nanocrystalline silicon particles with size less than 10 nm have been prepared by VHF plasma-enhanced decomposition of silane gas. Pulsed gas plasma processing, in which the nucleation and the growth period are controlled precisely, is turned out to be effective for the preparation of monodispersed nanocrystalline particles. Electrical properties of nanocrystalline silicon particles have been investigated by employing nanoscale electrodes, both planar and vertical configurations, prepared by electron-beam lithography. Coulomb blockade and Coulomb oscillations predominantly due to a single quantum dot are readily modeled as well as a minor contribution from the neighboring dots.Oxidation process of nanocrystalline Si particles is studied intensively in order to fabricate Si dots with size less than 5 nm. Retardation of oxidation rate has been observed due to the stress near the interface between oxide shell and Si core. Photoluminescence and electron emission have been observed from surface oxidized nanocrystalline silicon particles. Red light emission, observed at room temperature, can be divided into two components. Efficiency of the no-phonon-assisted band enhances with decreasing core Si size. Electron emission efficiency from nanocrystalline Si based cold emitter device is as high as 5 %, promising for display and lithography applications.