The electrical conduction properties of lateral and vertical silicon nanowires (SiNWs) were investigated using a conductive-probe atomic force microscopy (AFM). Horizontal SiNWs, which were synthesized by the in-plane solid-liquid-solid technique, are randomly deployed into an undoped hydrogenated amorphous silicon layer. Local current mapping shows that the wires have internal microstructures. The local current-voltage measurements on these horizontal wires reveal a power law behavior indicating several transport regimes based on space-charge limited conduction which can be assisted by traps in the high-bias regime (> 1 V). Vertical phosphorus-doped SiNWs were grown by chemical vapor deposition using a gold catalyst-driving vapor-liquid-solid process on higly n-type silicon substrates. The effect of phosphorus doping on the local contact resistance between the AFM tip and the SiNW was put in evidence, and the SiNWs resistivity was estimated.

International audienceWe present a single pump-down process to texture hydrogenated amorphous silicon solar cells. Mats of p-type crystalline silicon nanowires were grown to lengths of 1 µm on glass covered with flat ZnO using a plasma-assisted Sn-catalyzed vapor-liquid-solid process. The nanowires were covered with conformal layers of intrinsic and n-type hydrogenated amorphous silicon and a sputtered layer of indium tin oxide. Each cell connects in excess of 107 radial junctions over areas of 0.126 cm². Devices reach open-circuit voltages of 0.8 V and short-circuit current densities of 12.4 mA cm−2, matching those of hydrogenated amorphous silicon cells deposited on textured substrates

An interesting example of device combining amorphous material and nano‐ or microstructure is the wire solar cell. Solar cells based on silicon nano‐ or microwires have attracted much attention as a promising path for low cost photovoltaic technology. The key point of this structure is the decoupling of the light absorption from the carriers collection. In this work, we use numerical modeling to study two types of radial junction structures: (i) a p–n heterojunction for which p‐or n‐type crystalline silicon (c‐Si) wires are covered by a conformal n‐ or p‐ doped amorphous silicon (a‐Si:H) thin layer and (ii) thin film a‐Si:H p–i–n radial structures realized by conformal covering on thinner c‐Si wires. In the first structure, the a‐Si:H layer is only intended to form the heterojunction and light absorption takes place in the c‐Si wires, whereas in the second one, the absorber material is the a‐Si:H i‐layer and its thickness can be optimized to facilitate the carrier separation and collection. The potential of those both types of Si wires based solar cells will be compared according to the structure design and material properties. Furthermore, the sensitivity of the a‐Si:H p–i–n radial cells to the light‐soaking effect, i.e., the increase of deep defect density resulting from the breaking of weak silicon bonds, will be studied and compared to what is commonly observed on classical a‐Si:H planar p–i–n cells.