电子束纳米焊接与纳米切割

Nano-welding and nano-cutting with an electron beam

对小到1nm大到100nm的"纳米尺度",目前并没有成熟的原位物理加工技术。我们演示高强度电子束技术在纳米尺度上应用于原位物理加工的潜力,将高亮度场发射透射电子显微镜的电子束汇聚到直径1nm左右,可得到强度为106A/cm2量级的电子束。这样的电子束可被用来在直径几十纳米的单根金属或硅纳米线上实现结构修饰,切割出小孔、窄桥及缝隙等各类纳米尺度的图案结构。强度稍弱的电子束则可被用来实现在金属纳米线之间,或者金属纳米线与硅纳米线之间的焊接,也可被用于去除纳米线表面的氧化层。这些物理加工机制涉及高能电子穿越固体时各类非弹性散射造成的加热、非晶化、溅射、等离子气化等非线性效应。作为一项无污染且作用范围非常局域化的原位技术,它可直接应用于纳米结和纳米器件的修饰与制备。

A high-intensity electron beam with a intensity of 10^6 A/cm^2 has been applied to create holes, gaps, and other patterns of atomic and nanometer dimensions on a single semiconducting nanowire or a metallic nanowire. An electron beam with slightly weaker intensity can be used to weld individual nanowires, forming metal-to-metal or metal-to-semiconductor nanowire junctions. These applications of an intense electron beam result from various inelastic scattering processes between an incident high-energy electron and atoms of the specimen, that create heating, amorphization, ablation effects of the specimen, and some nonlinear effects such as plasma formation at the specimen surface. The localized, impurity-free electron beam nano-welding and nano-cutting techniques are ready for fabrication of nanodevices, and have a potential for large scale application.