Silicon nanocrystals (Si NCs) are intensively studied for optoelectronic and biological applications due to having highly attractive features such as band engineering. Although doping is often used to control the optical and electrical properties, the related structural properties of solely doped and codoped Si NCs are not well-understood. In this study, we report the boron (B) and/or phosphorus (P) distribution in Si NCs embedded in borosilicate glass (BSG), phosphosilicate glass (PSG), and borophosphosilicate glass (BPSG) using atom probe tomography (APT). We compared solely and codoped Si NCs grown at different temperatures so that we may compare the effects of codoping and temperature on the B and/or P distribution. Proximity histograms and cluster analyses reveal that there exist boron-rich layers surrounding Si NCs and also B–P clusters within the Si NCs. Raman spectra also show a structural change between codoped Si NCs in solids and free-standing codoped Si NCs. These results lead us to understand that codoped Si NCs disperse in polar solvents.

Developing highly efficient and durable electrocatalysts for hydrogen evolution reaction (HER) under both alkaline and acidic media is crucial for the future development of a hydrogen economy. However, state-of-the-art high-performance electrocatalysts recently developed are based on carbon carriers mediated by binding noble elements and their complicated processing methods are a major impediment to commercialization. Here, inspired by the high-entropy alloy concept with its inherent multinary nature and using a glassy alloy design with its chemical homogeneity and tunability, we present a scalable strategy to alloy five equiatomic elements, PdPtCuNiP, into a high-entropy metallic glass (HEMG) for HER in both alkaline and acidic conditions. Surface dealloying of the HEMG creates a nanosponge-like architecture with nanopores and embedded nanocrystals that provides abundant active sites to achieve outstanding HER activity. The obtained overpotentials at a current density of 10 mA cm −2 are 32 and 62 mV in 1.0 m KOH and 0.5 m H 2 SO 4 solutions, respectively, outperforming most currently available electrocatalysts. Density functional theory reveals that a lattice distortion and the chemical complexity of the nanocrystals lead to a strong synergistic effect on the electronic structure that further stabilizes hydrogen proton adsorption/desorption. This HEMG strategy establishes a new paradigm for designing compositionally complex alloys for electrochemical reactions.

n -type β-FeSi2/p-type Si heterojunctions were fabricated from β-FeSi2 films epitaxially grown on Si(111) by facing-target direct-current sputtering. Sharp film-substrate interfaces were confirmed by scanning electron microscopy. The current-voltage and photoresponse characteristics were measured at room temperature. They exhibited good rectifying properties and a change of approximately one order of magnitude in the current at a bias voltage of −1 V under illumination by a 6 mW, 1.31 μm laser. The estimated detectivity was 1.5×109 cm √Hz W at 1.31 μm. The results suggest that the β-FeSi2/Si heterojunctions can be used as near-infrared photodetectors that are compatible with silicon integrated circuits.

No abstract