Laser Ablation of Nanowires

In some ways, the laser ablation of nanowires is very similar to flow reaction synthesis, and fairly straightforward to conduct. First, a target is constructed from 

A hybrid approach to nanowire synthesis developed by Wu et al. [22] combines laser ablation with a flow reactor process, and has yielded superlattice nanowires of Si/SiGe. The role of the flow furnace is to produce Si nano wires, while the laser ablation process introduces Ge periodically into the vapor. The Ge is absorbed by the catalyst and incorporated into the forming nanowire. Through judicious control of the process, Wu s group has achieved superlattice periodicities of Si/ SiGe of approximately 250 nm. Moreover, the results of this study bode well for superlattice nanowire devices. 

Chemical Vapor Deposition and Plasma-Enhanced Chemical Vapor Deposition 

The use of liquid precursors is more involved than gases, but still easily manageable. Typically, an inert (carrier) gas such as Ar or N2 is bubbled through a vessel containing the liquid precursor (the vessel is often referred to as a bubbler ). Through judicious control of the liquid temperature and carrier gas flow rate, the concentration of the precursor in the gas-vapor mixture can be metered with a 

The vapor delivery system for sublimeable soM precursors is similar to liquid precursor delivery systems, specifically in its use of a carrier gas. Heating the solid precursor increases the sublimation rate. Sublimeable solid precursors are the most difficult to handle for the following reasons. The sublimation rate of a solid is a function of temperature, the quantity of the solid precursor in the vessel and the carrier gas flow rate. Consequently, the delivery rate of precursor to the chamber can vary during the course of consecutive experiments unless the quantity and form of the starting material is the same at the start of each experiment However, if care is taken this is typically not a problem. 

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