A detailed study on the growth of silicon nanowires by hot wire chemical vapor process: concept of critical size of Sn catalyst

The size of silicon nanowires (SiNWs) plays an important role for their application in nanoelectronic and nanophotonic systems. Therefore, it is of great interest to study the synthesis conditions of SiNWs in order to grow SiNWs with well-controlled manner to be integrated into a device. This paper includes a systematic study of the dependence of diameter and length of the SiNWs on the growth conditions. SiNWs were synthesized via vapor-liquid-solid (VLS) mechanism using a catalyst film of Sn nanoparticles on stainless steel (SS) substrate. The morphology and microstructure of SiNWs synthesized at different parameters were investigated with scanning electron microscopy and Raman spectroscopy. In this study, we have observed that there exists a minimum size of the catalyst to initiate the growth of SiNWs for a given set of process parameters. Furthermore, this work also addresses the difficulties associated with the growth of long SiNWs. Effect of filament temperature on the morphology of SiNWs has also been studied. It is observed that their dimensions and geometrical orientation are greatly influenced by the filament temperature. At filament temperatures between 1400 and 1600 degrees C, short SiNWs with random distributions are observed. Long and vertical SiNWs are found if the filament temperature was raised to 1800-1950 degrees C.