| 초록 |
Regarding thin film growth, the control of nucleation and growth is one of the most significant factors that decide the properties of the thin film structures. In particular, evaporation method that involves vacuum process usually requires high vacuum or ultra-high vacuum to obtain highly dense thin film structures. During the conventional evaporation process, evaporated species traverse the deposition chamber without collision due to a long mean free path. Reaching a cool substrate, the adatoms nucleate heterogeneously and growth occurs resulting in a dense microstructure. In this research we demonstrate that the dense structure can be converted into nanoporous structures by simply increasing background pressure up to a few Torr. Adjusting the background pressure enables controlling morphology and porosity of the obtained film structures, where nano-sized particulates are aggregated. Applying this technique to Sn, we obtain highly porous, additive-free Sn anodes of Li-ion batteries that show enhanced cyclability and charging performance. Besides, Au and Ag nanoporous structures made by this method conduce to enhanced sensing performance as they are utilized for surface enhanced raman spectroscopy compared to commercial ones. |
