ABSTRACT
Tree-like is a relatively frequent nano-and microstructural type, obtained for a series of inorganic compounds, mostly for silicon, silica, and carbon. Generally, they are closely related to nanowires, which are modi£ed with branches; sometimes they are produced from them1 and can appear together with other nanostructures. In the case of silicon, the structure and electronic properties of its nanotrees using large-scale quantum mechanical simulations were investigated.2 Electronic structure analysis showed that the formation of nanotrees was accompanied by a narrowing of the HOMO-LUMO gap; this fact could lead to their application in molecular devices due to the predicted enhancement in the conducting properties. Si nanotrees were found to be suitable also for thermoelectrical applications.3 The effects of trimethylaluminum (TMA) on silicon nanowires grown by chemical vapor deposition (CVD) were investigated in the 650°C-850°C growth temperature range using Au as the growth catalyst and SiH4 in H2 carrier gas as the Si precursor.4 Depending on the substrate temperature and TMA partial pressure, the structure’s morphology evolved from wires to tapered needles, pyramids, or nanotrees (the TMA presence was linked, in particular, to a branched growth leading to Si nanotrees).
