Control of Particle Size and Position of Nano-crystalline Silicon

随着硅纳米结构制备技术的不断进步，人们有可能观察到硅量子点特有的电子输运现象，如单电子隧穿、弹道输运、可见光致发光和电子发射等。采用甚高频等离子体增强分解硅烷气体的方法制备了尺寸小于10 nm的纳米晶硅颗粒。脉冲气体等离子体工艺可以精确地控制成核和生长周期，是制备单分散纳米晶颗粒的有效方法。采用电子束光刻技术制备纳米级平面和垂直结构电极，研究了纳米晶硅颗粒的电学性能。主要由单个量子点引起的库仑阻塞和库仑振荡以及邻近点的少量贡献很容易建模。为了制备尺寸小于5nm的硅点，对纳米晶硅颗粒的氧化工艺进行了深入研究。氧化壳与硅芯交界面附近的应力对氧化速率有延缓作用。从表面氧化的纳米晶硅颗粒中观察到光致发光和电子发射。红光发射，在室温下观察，可分为两个组成部分。无声子辅助带的效率随芯硅尺寸的减小而增强。纳米晶硅冷发射器件的电子发射效率高达5%，在显示和光刻领域具有广阔的应用前景。

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.