• Bulkin, Pavel
• Wang, Weixi
• Maurice, Jean-Luc
• Ngo, Éric
• Foldyna, Martin
• Zhang, Zhengyu
• Johnson, Erik, V.
• Pere, Roca I. Cabarrocas

Abstract

International audience ; We report silicon nanowire (SiNW) growth with a novel Cu-In bimetallic catalyst using a plasma-enhanced chemical vapor deposition (PECVD) method. We study the structure of the catalyst nanoparticles (NPs) throughout a two-step process that includes a hydrogen plasma pre-treatment at 200 • C and the SiNW growth itself in a hydrogen-silane plasma at 420 • C. We show that the H 2-plasma induces a coalescence of the Cu-rich cores of as-deposited thermally evaporated NPs that does not occur when the same annealing is applied without plasma. The SiNW growth process at 420 • C induces a phase transformation of the catalyst cores to Cu 7 In 3 ; while a hydrogen plasma treatment at 420 • C without silane can lead to the formation of the Cu 11 In 9 phase. In situ transmission electron microscopy experiments show that the SiNWs synthesis with Cu-In bimetallic catalyst NPs follows an essentially vapor-solid-solid process. By adjusting the catalyst composition, we manage to obtain small-diameter SiNWs-below 10 nm-among which we observe the metastable hexagonal diamond phase of Si, which is predicted to have a direct bandgap.

Topics

• nanoparticle
• impedance spectroscopy
• phase
• experiment
• Hydrogen
• transmission electron microscopy
• Silicon
• annealing
• chemical vapor deposition