Advanced VLS growth of gold encrusted silicon nanowires Mediated by porous Aluminium Oxide template. (March 2021)

• Record Type: Journal Article
• Authors: Deepu, Bagur R.; Anil, Seegehalli M.; Savitha, Purakkat; Basavaraju, Yeriyur B.
• Is Part Of: Vacuum. Volume 185(2021)
• Publication Date: 2021-03
• Subjects: Porous anodic aluminium oxide -- Au-nanodroplets -- Vapor-liquid-solid growth -- Chemical vapor deposition -- Silicon nanowires -- Nano encrustations; Vacuum -- Periodicals; 621.55
• DOI: 10.1016/j.vacuum.2020.109991
• Languages: English
• ISSNs: 0042-207X

Abstract

Abstract: A highly efficient technique for the generation of dense and homogeneous Au-nanodroplets using Anodic Aluminium Oxide template (AAO) for the fabrication of single crystal gold encrusted array of silicon nanowires (SiNWs) was successfully developed. In interest of extending AAO's practical applicability, the Au-thin film sandwiched between Si-substrate and AAO was torn-up into small nanodroplets at annealing temperature followed by removal of AAO template before VLS growth instead of growing SiNWs directly in presence of AAO template. It's observed that smaller Au-nanodroplets are mandatory to yield dense array of SiNWs, further, size of formed Au-droplets is directly relied on AAO pore-size. Thus, construction of desired pore diameter on AAO was critically controlled by the application of voltage in presence of different etchants (sulfuric acid (SA), oxalic acid (OA) and phosphoric acid (PA)). Among the different etchants used SA demonstrated smaller AAO-pore size at a specific voltage and concentration. Further, obtained smaller Au-nanodroplets (from SA etched AAO) exhibited a denser array of SiNWs on VLS growth at particular set of experimental conditions. Characterization by advanced techniques such as UV–Vis spectroscopy, Micro-Raman spectroscopy, Scanning Electron Microscope (SEM), Transmission Electron Microscopy (TEM), High-Angle Angular Dark Field Scanning Transmission Electron Microscopy (HAADF-STEM) and Energy Dispersive X-ray Spectroscopy (EDX) revealed that the formed SiNWs were of 199 ± 43 nm diameter with well-decorated gold nano encrustations on the surface and at the tip. The formed SiNWs were in resemblance with SiNWs obtained from high precision e -beam Lithography, evidencing the superiority of the current method. Graphical abstract: The study is directed to investigate the effect of Anodic Aluminium Oxide (AAO template) pore diameter on the formation of Au-nanodroplets as a catalysts for the VLS growth of SiNWs. Interestingly, SiNWs obtained from Au-nanodroplets drawn from e -beam lithography was in resemblance with the SiNWs of current methodology. Further, control experiments with negligible nanodroplets/nanowires signifying the superiority of the developed methodology. In situ growth of these gold encrusted nanowire provides an added advantage in the field of plasmonic and bio-sensors. Image 1 Highlights: Generation of nano-porous Anodic Aluminium Oxide template (AAO) by anodizing aluminium film in presence of different acidic solutions under applied voltage. Stabilization of annealing parameters for the conversion of Au-thin film into homogeneous Au-nanodroplets at different annealing temperature and time intervals in presence of AAO. Fabrication of single crystal gold encrusted array of silicon nanowires (SiNWs) on VLS growth from synthesized homogeneous Au-nanodroplets. Comparison of developed methodology against e -beam lithography.