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Competing interest The authors declare that they have no competing interests. Authors’ contributions MZ and CK carried out the synthesis, scanning electron microscopy and X-ray diffraction. The optical properties were measured by AO. The calculations were carried out by MZ who was also wrote the manuscript. All authors read and approved the final manuscript.”
“Background Attractive interdisciplinary research areas between electronic and photonic materials have been developed by modern semiconductor nanotechnology. Si nanostructures are particularly important because solar cells using Si have widely been investigated [1, 2], and optical interconnections among integrated Si circuits have also been proposed by developing Si-based photodiodes and optical modulators CB-839 in vitro [3, 4]. Therefore, many types of Si nanostructures, such as nanocrystals (NCs), nanodots, and selleck kinase inhibitor porous nanostructures, were reported by employing various fabrication processes [5–14]. Moreover, fabrication processes of the Si nanostructures using ‘top-down’ lithography Endocrinology inhibitor techniques were strongly motivated for the purpose of applying the Si nanostructures to electronic

and photonic devices. We have recently proposed a fabrication process of Si nanodisk (ND) arrays, where the Si NDs are formed by damage-free neutral beam (NB) etching for Si thin films covered with etching masks of Fe

nanoparticles which are regularly aligned by bio-protein engineering [15–20]. This fabrication process using the bio-templates enables us to prepare closely packed high-density Si for NDs with the intentionally designed precise size and spacing in a nanometric scale with flexible film stacking. We have also observed intense photoluminescence (PL) emissions in a visible light region with fast decay times ranging from 10 ps to 2 ns [20]. The fast decaying PL characteristics reflect the dynamics of photo-excited carriers in this high-density Si ND array system, in which wavefunctions of photo-excited carriers overlap among Si NDs to some extent, and the carriers can transfer among the NDs [20]. Photo-generated or electrically injected carriers need to be effectively transferred among Si NDs for the optical applications to solar cells or light-emitting diodes. The spatial transfer of the carriers in nanostructures can also be affected by thermal effects, such as thermal hopping or escape. Therefore, in this paper, we investigate the detailed temperature dependence of time-resolved PL and the related carrier dynamics in these high-density Si ND arrays. Different types of PL quenching mechanism can be identified, and the activation energies for the PL thermal quenching are deduced from the temperature dependences of the PL intensity.