William McSweeney

Metal-assisted chemical etching of silicon and the behavior of nanoscale silicon materials as Li-ion battery anodes

This review outlines the developments and recent progress in metal-assisted chemical etching of silicon, summarizing a variety of fundamental and innovative processes and etching methods that form a wide range of nanoscale silicon structures. The use of silicon as an anode for Li-ion batteries is also reviewed, where factors such as film thickness, doping, alloying, and their response to reversible lithiation processes are summarized and discussed with respect to battery cell performance. Recent advances in improving the performance of silicon-based anodes in Li-ion batteries are also discussed. The use of a variety of nanostructured silicon structures formed by many different methods as Li-ion battery anodes is outlined, focusing in particular on the influence of mass loading, core-shell structure, conductive additives, and other parameters. The influence of porosity, dopant type, and doping level on the electrochemical response and cell performance of the silicon anodes are detailed based on recent findings. Perspectives on the future of silicon and related materials, and their compositional and structural modifications for energy storage via several electrochemical mechanisms, are also provided.

Doping controlled roughness and defined mesoporosity in chemically etched silicon nanowires with tunable conductivity

By using Si(100) with different dopant type (n++-type (As) or p-type (B)), we show how metal-assisted chemically etched (MACE) nanowires (NWs) can form with rough outer surfaces around a solid NW core for p-type NWs, and a unique, defined mesoporous structure for highly doped n-type NWs. We used high resolution electron microscopy techniques to define the characteristic roughening and mesoporous structure within the NWs and how such structures can form due to a judicious choice of carrier concentration and dopant type. The n-type NWs have a mesoporosity that is defined by equidistant pores in all directions, and the inter-pore distance is correlated to the effective depletion region width at the reduction potential of the catalyst at the silicon surface in a HF electrolyte. Clumping in n-type MACE Si NWs is also shown to be characteristic of mesoporous NWs when etched as high density NW layers, due to low rigidity (high porosity). Electrical transport investigations show that the etched nanowires exhibit ...

Mesoporosity in doped silicon nanowires from metal assisted chemical etching monitored by phonon scattering

Higher Education Authority (Irish Government’s Programme for Research in Third Level Institutions, Cycle 4, National Development Plan 2007–2013); Irish Research Council (Award No. RS/2011/797); Science Foundation Ireland (under the National Access Programme (NAP 417))

Fabrication and Characterization of Single-Crystal Metal-Assisted Chemically Etched Rough Si Nanowires for Lithium-Ion Battery Anodes

Higher Education Authority (under the framework of the INSPIRE programme, funded by the Irish Governments Programme for Research in Third Level Institutions, Cycle 4, National Development Plan 2007-2013)

Raman Scattering Spectroscopy of Metal-Assisted Chemically Etched Rough Si Nanowires

Higher Education Authority (under the framework of the INSPIRE programme, funded by the Irish Governments Programme for Research in Third Level Institutions, Cycle 4, National Development Plan 2007-2013)