Vapor–Liquid-Solid silicon wires’ synthesis catalyzed by a low-surface tension post-transition metal: effect of process parameters

Abstract

In this work, we report on Vapor–Liquid-Solid growth of silicon wires (SiNWs) catalyzed by bismuth, a low-surface tension post-transition metal. The bismuth catalyst is synthesized by two different processes: in ex situ by annealing bismuth-coated substrates using rapid thermal annealing (RTA) process under hydrogen gas, and in situ in a plasma-enhanced chemical vapor deposition (PECVD) using hydrogen plasma. We show that by using RTA process, oxide-free bismuth particles were successfully grown. X-ray diffraction (XRD) analysis depicts pure bismuth planes proving the high crystalline quality of the obtained structures. Quasi-spherical and homogeneously distributed bismuth particles were obtained at 450 °C during 5 min. The growth temperature and time effect on SiNWs’ synthesis were studied. Due to its low-surface tension, bismuth has a low catalytic activity resulting in the growth of SiNWs achieved at 600 °C for 20 min. The obtained structures’ density was very low. An improvement of the density was achieved with longer duration (45 min), as more bismuth particles were active to catalyst the growth. In addition, bismuth particles formed in PECVD under hydrogen plasma were used as catalyst for in situ growth. While they both were kinked, these structures were straighter than the SiNWs catalyzed by particles obtained by RTA process.