Jeffrey Hong edited subsection_Laser_Ablation_Laser_ablation__.tex  almost 9 years ago

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\subsection{Laser Ablation}  Laser ablation is a method of nanowire synthesis through ablation of a mixture of GaN and Ga2O3 powders in a 3:1 molar ratio. Similarily Similar  to VLS, the powders are placed in a heated and pressurized furnace with a temperature of 900 C and a working pressure of 400 Torr. A 248 nm, 10 Hz laser is then pulsed onto the powders for a total period of 2 hours, creating a large amount of GaN nanowires. This is known as the “oxide-assisted growth mechanism”, in which a series of oxidation and reduction reactions between the initial GaN and Ga2O3 powders form nucleation sites when exposed to the laser. \cite{Shi_2001} Compared to VLS, this synthesis takes a larger period of timeas well  without replacing expensive equipment or reagents. Though the chemical reagents are different from the feed gases found in VLS, the process itself still requires a contained furnace with both high heat and pressure, similar to VLS. pressure.  The actual nanowires obtained from the process are not very specific, as they range from diameters of 20 to 120 nm. Their lengths are a few micrometers as well, which results in entanglement of the nanowires. When observed under high resolution transmission electron microscopy, the same lattice spacing and intersection angles were observed when compared to GaN nanowires synthesized using VLS. \cite{Shi_2001}