Development of novel approaches to the solution synthesis of Si and Ge nanoparticles and nanowires

The last number of years has seen the development of a wide range of nanoscale materials exhibiting new or improved properties with considerable potential for electronic, energy, and sensing applications. One could argue confidently that energy applications of nanomaterials will be among the more significant, encompassing the diverse fields of energy generation, transmission, storage and consumption. As a result of their unique optical properties, II-VI and IV semiconductor nanomaterials have received exceptional research attention, with countless promising studies already reported. However, if the potential of nanomaterials is to be fully realised with micro/macroscale systems, then nanocrystal purity and large-scale assembly must be achieved. Herein is described a number of novel synthetic methods which were developed to produce silicon and germanium nanowires and nanoparticles of various sizes, morphologies and surface chemistry in solvents under ambient and supercritical conditions. The thermal degradation of organometallic precursors at high temperatures and/or high pressures is used in conjunction with coordinating and non-coordinating ligands and solvents for the steric stabilization of emerging nanocrystal nuclei in solution. The synthetic strategies to and complete material characterisation of well faceted tetrahedral and pseudo-spherical shaped silicon nanocrystals, metal surface nucleated silicon and Ge/SiOx core-shell nanowires, catalyst-free self-seeded Ge nanowires and Ge nanocrystal functionalized colloidal carbon is outlined.