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Gas Source Molecular Beam Epitaxy (GS-MBE) coupled with self assembled Au particles has been successfully used to grow GaAs nanowires.\cite{Plante_2006}. Briefly, GS-MBE works as follows...Samples are carfully prepared and so that a clean single crystal face is oriented towards the beam source. The beam source is placed at a sufficient distance to allow uniform deposition onto the surface. Growth rates depend on the flux of gas used and formation rate of clusters.\cite{9780199544219} The mechanism of Nanowire growth reveals that the role of the Au catalyst is different than that described above for VLS and MOVPE. MBE GaAs nanowire growth was studied as a function of temperature, As:Ga ratio, Au seed particle size (20-800nm), revealing two main mechanism with different rates of nanowire formation.\cite{Plante_2006} For Au catalyst below the size of 105-130nm, the height of the wire is driven by the diffusion of Ga/As gas from the walls up to the tip of the wire. For catalyst greater than 103nm, bulk diffusion through the metal catalyst is responsible for nanowire growth.  Bulk synthesis of GaAs include an electrodeposition of gold particles method. While Au catalyst have been used in evaporated, aerosol and colloid particle forms, these methods make it challenging to grow NW in a pattern, making the techniques less dependable for high redproducibility and consistency. Electrodeposition in conjunction with lithography has succesfully been used to produce nanoscale patterns.\cite{Jafari_Jam_2015} The method works as follows...nanoimprint lithography is used to define a pattern, resist residues were removed by ion etching, electrodeposition (a process that uses electric current to reduce dissolved gold metal cations so that they form a coherent metal coating on the electrode's exposed parts) occurs by placing the patterned substrate/resist wafer into a solution of gold, after gold deposition resist stripping is finished so that only the substrate and gold pattern are left.\cite{Jafari_Jam_2015} Advantages (compared to other methods such as thermal evaporationg) include higher throughput, and reduced gold consumption by a factor of 300.In addition to advances in understanding of VLS NW growth and ternary phase diagrams for GaAs NW growth in the past years, an understanding of Au catalyzed GaAs NW shape (specifically facets) has also been achieved. The orientation and shape of NW facets determine the heterointerface of GaAs and hence its properties. Furthermore, Facet transformation has been reported as effecting growth rate and composition uniformity of NW shell during synthesis.\cite{Zheng_2013} A reuleauxtriangle with three [112] curved surfaces is determined to be the actual shape at the growth site instead of the previously believed hexagonal surface [111].The crystal structure is thermodynamically unstable and changes to [112] facets in a polarity-driven vapor solid growth mechanism that occurs simultaneously. When enough energy is supplied to overcome the activation barrier associated with facet change it can also adopt [110] facets. Jiang and coworkers developed a model based on the VLS nucleation theory to explain these findings.\cite{Jiang_2014}  Various growth parameters may be tuned to achieve specific NW shape. HCl has been used in Au catalyzed GaAs NW growth to suppress wurtzite like crystal growth in favor zince blende crystal structure growth. The Chlorine interacts wit the Ga species to prevent Ga to contributing to growth.\cite{Jacobsson_2014}   Axial and radial growth are the two directions of growth taking place during nanowire growth for MOVPE and VLS. Radial growth occurs when species are absorbed on the sidewalls of the nanowire. It is possible for these species to be further absorbed towards the Au catalyst causing the toe be incorporated into the axial growth.