About Some Fundamental Aspects of the Growth Mechanism Vapor-Liquid-Solid Nanowires

Abstract

This study provides the formation of semiconductor nanowires (NWs) with a singular facet and a curved end surface by the vapor-liquid-solid (VLS) process that is analyzed and explained in details. Given the evidence, it is confirmed that the wettability of a liquid catalyst droplet on a crystal surface and the contact angle between the droplet and crystal play an essential role in the VLS process of NWs development. It is shown that for the VLS mechanism, the formation of NWs depends on the reduction in activation barrier to crystallization caused by the release of surplus-free energy by a spheroidizing drop in the region of the triple junction during the process of lowering surface area. This decreases the necessary supersaturation for the development of NW vertex facets at a fixed growth rate. The source of the extra free energy that drives the catalyst droplet movement during the steady-state development of NWs is the droplet’s outer surface. During the formation of NWs, those angles of inclination of the lateral surface NWs and droplet contact are obtained at which the solid/vapor, solid/liquid, and liquid/vapor interfaces experience the smallest increase in free energy. The wetting hysteresis is demonstrated to occur at the vertex of NWs, and the contact angle of a catalyst droplet may be regarded as an independent and fully-fledged thermodynamic parameter of the system’s state.

Machine Learning Methods to Improve Crystallization through the Prediction of Solute–Solvent Interactions

“…In the pharmaceutical industry, crystallization is vital for producing valuable products such as active pharmaceutical ingredients [5] and organic fine chemicals [6], where the purity and morphology of crystals can significantly impact drug efficacy and safety. The burgeoning field of engineered nanoparticles and crystals for the electronics industry also relies heavily on crystallization, integral in advancing technologies in areas like semi-conductors [7,8] and battery production [9]. Additionally, biotechnology products, such as protein and fat crystals, are gaining prominence due to their applications in drug design and medical research [10,11].…”