Direct contact four-point probe characterization of Si microwire absorbers for artificial photosynthesis

We present a facile approach that achieves four-point electrical characterization of silicon microwires fabricated using a bottom-up vapour-liquid-solid process. Tungsten probes are brought into direct contact with silicon microwires using piezoelectrically driven probe actuators. This technique can be applied to silicon microwires without the need for high-temperature lithographic preparation or the additional use of In/Ga to ensure reliable electrical contact between the probe and the wire. Comparison between two-point probe and four-point probe measurements demonstrates the robustness of the four-point approach. Significantly, the four-point characterization technique is not impacted by native oxides at the microwire/tungsten probe interface. The four-point technique can be applied to sense electrical responses in half-cell and full-cell representations of artificial photosynthesis systems, regardless of catalysts or functional groups attached to the microwire sidewalls.