Understanding the Role of Seed Particle Material on III-As Nanowire Growth

III-V semiconductor nanowires have attracted extensive research interests over the past few decades due to their unique geometry and great potential for promoting new functionalities in future electronics, light-emitting diodes and solar cells. However, in order to push this technology beyond the laboratory level, it is essential to combine it with the current Si-based semiconductor industry for affordable production. The synthesis of III-As nanowires relies mostly on the use of Au as seed particle, which as a result of high diffusivity of Au in Si, limits the possibility to integrate III-As nanowires into Si devices.
The purpose of this thesis is trying to get a better understanding of which properties might be desirable for a material to act as seed particle to assist nanowire growth.
This thesis studies Sn-seeded growth of GaAs, InAs and InGaAs nanowires by MOVPE, and how the growth process can be controlled to tailor the nanowire morphology and crystal phase to some exten. The in-situ formation of Sn particles on various substrates has been investigated. The temperature range and the flow of growth precursors for Sn-seeded nanowire growth differ a lot from nanowire growth from Au seed particles. In contrast to Au-seeded nanowires, Sn-seeded GaAs and InAs nanowires mostly exhibit zincblende crystal phase. Furthermore, a big advantage of using Sn as seed material is the simultaneous incorporation of the particle material into the nanowire during growth, leading to nanowires with high n-type doping profile.