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• Blister-free boron-doped poly-Si layers are obtained by PECVD through optimization of the deposition temperature and gas ratio. • The process developed is approaching the industrial standards (large area KOH-polished wafers, SiOx growth included in standard RCA cleaning, semi-industrial PECVD tool). • High and homogeneous surface passivation properties are obtained (iVoc = 734 mV and J0 = 7 fA•cm-2). • Conductive spots detected by C-AFM are not mirroring pinholes within the interfacial SiOx layer.

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.

The current climate and energy crisis urgently needs solar cells with efficiencies above the 29% single junction efficiency bottleneck. Silicon/perovskite tandem solar cells are a solution, which is attracting much attention. While silicon/perovskite tandem cells in 2-terminal and 4-terminal configurations are well documented, the three-terminal concept is still in its infancy. It has significant advantages under low light intensities as opposed to concentrated sunlight, which is the critical factor in designing tandem solar cells for low-cost terrestrial applications. This study presents novel studies of the sub-cell performance of the first three-terminal perovskite/silicon selective band offset barrier tandem solar cells fabricated in an ongoing research project. This study focuses on short circuit current and operating voltages of the sub-cells under light intensities of one sun and below. Lifetime studies show that the perovskite bulk carrier lifetime is insensitive to illumination, while the silicon cell's lifetime decreases with decreasing light intensity. The combination of perovskite and silicon in the 3T perovskite-silicon tandem therefore reduces the sensitivity of V OC to light intensity and maintains a relatively higher V OC down to low light intensities, whereas silicon single-junction cells show a marked decrease. This technological advantage is proposed as a novel advantage

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Articles you may be interested inDirect determination of the band offset in atomic layer deposited ZnO/hydrogenated amorphous silicon heterojunctions from X-ray photoelectron spectroscopy valence band spectra

Conductive-probe atomic force microscopy (CP-AFM) measurements reveal the existence of a conductive channel at the interface between p-type hydrogenated amorphous silicon (a-Si:H) and n-type crystalline silicon (c-Si) as well as at the interface between n-type a-Si:H and p-type c-Si. This is in good agreement with planar conductance measurements that show a large interface conductance. It is demonstrated that these features are related to the existence of a strong inversion layer of holes at the c-Si surface of (p) a-Si:H/(n) c-Si structures, and to a strong inversion layer of electrons at the c-Si surface of (n) a-Si:H/(p) c-Si heterojunctions. These are intimately related to the band offsets, which allows us to determine these parameters with good precision.

International audienceThe temperature dependence of the capacitance of very high efficiency silicon heterojunction solar cells exhibits an anomalously large increase with temperature that cannot be explained under the usual depletion approximation. Based on a full calculation of the capacitance, we show that this large increase of capacitance with temperature of p-type hydrogenated amorphous silicon (a-Si:H)/n-type crystalline silicon (c-Si) heterojunctions occurs when a strong inversion layer at the c-Si surface appears. It is further shown that due to the promotion of inversion as the temperature increases, the temperature at which strong inversion appears depends on the valence band offset and position of the Fermi level in a-Si:H. Therefore, a simple analysis of the temperature dependence of silicon heterojunction solar cells' capacitance can be used to reveal the presence of a strong inversion, to study details of the band diagram and to get insight into the heterointerface