Ion-assisted growth of aligned silicon nanocones and nanowhiskers with indium as a growth promoter
Bettge, Martin; Abraham, Daniel; Burdin, Stephan A.; MacLaren, Scott W.; Petrov, Ivan G.; Sammann, Ernest A. United States
An ion-assisted Vapor-Liquid-Solid (VLS) process has been developed for the growth of large area silicon nanowhisker arrays. The nanowire growth is initiated by molten indium droplets predeposited on a Si wafer or Si-coated substrate. Growth occurs at about 190°C in an ambient containing argon and hydrogen. Atomic silicon is supplied by DC magnetron sputtering. Ion bombardment of the substrate results in self-supported high-aspect ratio structures grown at rates up to 200 nm/min. Final whisker height is limited by physical sputtering of the indium seed. Whisker diameters are on the order of 10-100 nm and the structure aerial density is between 10^9 and 10^10 cm-².
Key advantages of the developed process are (i) the replacement of the chemical vapor species used in conventional CVD-VLS by an atomic silicon source, (ii) growth at low substrate temperatures, and (iii) the ability to form the nanowhisker array on any substrate on which a thin Si film can be deposited.