Energy-Conversion Properties of Vapor-Liquid-Solid–Grown Silicon Wire-Array Photocathodes

Abstract

Silicon wire arrays, though attractive materials for use in photovoltaics and as photocathodes for hydrogen generation, have to date exhibited poor performance. Using a copper-catalyzed, vapor-liquid-solid–growth process, SiCl4 and BCl3 were used to grow ordered arrays of crystalline p-type silicon (p-Si) microwires on p+-Si(111) substrates. When these wire arrays were used as photocathodes in contact with an aqueous methyl viologen2+/+ electrolyte, energy-conversion efficiencies of up to 3% were observed for monochromatic 808-nanometer light at fluxes comparable to solar illumination, despite an external quantum yield at short circuit of only 0.2. Internal quantum yields were at least 0.7, demonstrating that the measured photocurrents were limited by light absorption in the wire arrays, which filled only 4% of the incident optical plane in our test devices. The inherent performance of these wires thus conceptually allows the development of efficient photovoltaic and photoelectrochemical energy-conversion devices based on a radial junction platform.

Photoelectrochemical Hydrogen Evolution Using Si Microwire Arrays

“…Si microwire arrays were grown using a process similar to that described previously. 1,2 Boron-doped p + -Si (111) wafers, having a resistivity of < 0.001 ·cm (Silicon Quest International), were used as growth substrates. The wafers were coated with 450 nm of thermal oxide that had been patterned with 4-μm-diameter circular holes arranged on a square lattice with a 7 μm pitch.…”

“…These growth conditions have been shown to yield p-Si wires with active doping concentrations of ~ 10 17 cm -3 . 1,3 …”

Functional integration of Ni–Mo electrocatalysts with Si microwire array photocathodes to simultaneously achieve high fill factors and light-limited photocurrent densities for solar-driven hydrogen evolution

“…22 The growth wafers were patterned with 3 mm diameter Cu catalysts located via photolithography in a square pattern with a 7 mm pitch. Highly doped n + -Si emitters were formed by use of a phosphorousdoped spin-on-glass.…”

Approaching Gas Phase Electrodeposition: Process and Optimization to Enable the Self‐Aligned Growth of 3D Nanobridge‐Based Interconnects

“…These structures have a high surface-to-volume ratio and should be useful for any catalytic process, like batteries or cells for water splitting applications. [ 23 ] An . Programmable gas phase nanomaterial electrodeposition system.…”