第五章 新材料之纳米材料ppt.pptVIP

主要内容 纳米材料的定义与特性 不同尺寸和形状的银纳米粒子具有不同的光学性质 不同尺寸的钴纳米粒子具有不同的磁学性质 纳米材料和纳米技术的研究意义 纳米加工 Towards 3D Scaffolding of Nanoscale Structures Silicon Nanocrystals Prof. Fabian Pease Stanford Microstructures Group Silicon Nanocrystals Nanometer sized crystals of Silicon Interesting Applications Light amplification using Silicon nanocrystals（光放大） Nanocrystal Based Memory? Fabrication Ion implantation of Si on quartz followed by high-temperature thermal annealing. LPCVD using SiH4 at ~580?C * “Optical gain in silicon nanocrystals” L. Pavesi, et al. Nature 408, 440 - 444 (23 Nov 2000) ? Narrow Channel MOSFET Memory based on Silicon Nanocrystals and Charge Storage Characteristics, Y.Shi et al, Proc. of 57th Device Res. Conf. USA, p.136, 1999 Problems and Challenges How to grow nanocrystals at a desired location over a large area? Some viable approaches : Patterning Re-crystallization Chemical Nanotemplating（模板） and growth Graphoepitaxy（图形外延） Nano-imprint Lithography (NIL)纳米印刷 Emboss a mold pattern on the resist Anisotropic etch to transfer the pattern Sub-10nm resolution – mold made by E-beam Parallel Process Source: /~chouweb/newproject/page3.html Nanocrystals by NIL（纳米印刷） NIL based patterning Deposit thin layer of amorphous Si on a substrate Transfer patterns using NIL Metal Induced Crystallization – Nickel（金属诱导晶化） Deposit 5-10nm thick Ni film on the patterned substrate Heat treatment at 500?C in a nitrogen ambient Ref: T. I. Kamins et al. “Positioning of Self-Assembled Single Crystal Ge Islands by Silicon Nanoimprinting, Appl Phys Lett 74 (12), 1773, 1999 Single Point Nucleation Methods单点成核法 Imprint Technology Deposit a-Si on oxide Press Ni coated Si tips at 0.15MPa 560 ?C anneal in N2 ambient for 7 hrs. Focused Ion Beam Si+, Ge, Pt etc Temperature ~ 200-300 ?C Chemical Templating and Growth-CTG Self Assembled Monolayers (SAM) Molecular assemblies formed by adsorption of an active surfactant（表面活化剂） on a solid surface. Ordered confirmation attained to minimize