Growth Study of Silicon Nanowires Synthesized Via Plasma-Assisted VLS Using Tin Catalysts

Abstract

It is for this reason that an alternative metal to gold has been investigated for the synthesis of semiconductor NWs. From this point of view, Tin can be used as an alternative candidate because of its low eutectic point (232 ° C) and low solubility in Si. Thin films of the Sn catalyst, with 1 nm of thickness, were prepared by the thermal evaporation method at a pressure of 2×10 -6 mbar vacuum on crystalline (100) silicon wafer c-Si and hydrogenated amorphous silicon coated c-Si a-Si:H/ c-Si substrates at room temperature. The samples were loaded into PECVD chamber, Sn nanoparticles were formed by exposure to 100 sccm of H 2 plasma for 2 min, SiNWs were then grown for 20 min by introducing pure silane (SiH4) into the reactor with a flow rate of 5 sccm at a substrate temperature between 400 and 600 °C. SEMs showing that the Tin catalyzed SiNWs are tapered in nature and randomly oriented. The density and the morphology of the NWs are influenced by the growth temperature and by the substrate. Abstract In the present work, silicon nanowires (SiNWs) have been grown on crystalline silicon (Si) (100) oriented and hydrogenated amorphous silicon a-Si:H coated c-Si (a-Si: H/c-Si) substrates by plasma-enhanced chemical vapor deposition (PECVD) via the vapor-liquid-solid (VLS) process at different temperature. Tin (Sn) catalyst coating with a thickness of 1 nm were used as metal catalysts. A hydrogen plasma was applied to reduce the oxide and to form Sn droplets. SiNWs were then grown by introducing pure silane (SiH4) into the reactor with a flow rate of 5 sccm and a chamber pressure of 1.33 mbar, at a substrate temperature between 400 and 600°C. Their morphological and surface characteristics have been investigated using Hitachi S4800 scanning electron microscopy (SEM). Morphology obtained from SEM shows tapered growth of NWs with a distinctively sharp tip.