Semiconductor nanowires (NW) are becoming increasingly important due to their novel electronic, photonic, thermal, electrochemical and mechanical properties and potential applications thereof in fields such as electronics and opto-electronics. (Yang 2010) (Dasgupta 2014) (Li 2006) (Yan 2009) There does not seem to be a limit to the innovative electronic designs that are being created to test these properties. Gallium Arsenide (GaAs) NWs have been explored for a myriad of possible devices including, transistors, photo-detectors, LED, solar cells, and nanolaser devices. In order for applications in these fields to be successful there must be synthetic control of NW quality; including, synthetic control of phase puritiy, chemical composition, surface:volume ratio, NW length, NW diameter, and NW shape.(Fang 2014) (Dick 2014) All these NW attributes consequently control the NW properties that are of interest, and even small variations or inconsistencies can have large effects on NW performance. This article reviews the methods of GaAs NW synthesis and the most recent electronics that have been designed using GaAs NWs. The topics to be reviewed are divided into two sections, one of synthesis and one of applications.
Synthesis technique advancement is key to being able to produce high quality NW for electronics applications. Synthesis of III-V NWs have undergone many changes and improvements as of late. (Fang 2014) (Dick 2014) (Dasgupta 2014) In particular, the many methods can generally be categorized as gold dependent and gold independent. But in addition to new synthesis methods, insight into the morphology of the NW has also been gained.
Many of the common NW synthesis techniques can be used for the synthesis of III-V GaAs NW, such as Vapor-Liquid-Solid (VLS), molecular beam epitaxy (MBE) and, metal organic chemical vapor deposition (MOCVD).(Meyyappan 2009) There also exist many techniques that improve on these earlier methods such as laser ablation.
Vapor-Liquid-Solid growth (VLS) is common for NW synthesis and has been used for GaAs NW growth.(Hu 1999) (Dubrovskii 2015) (Dasgupta 2014) A catalytic liquid phase droplet (in the case of GaAs NW, the catalyst could be Cu, Ag or Au) is formed on the solid surface of the substrate then, the droplet quickly absorbs the vapor containing precursors