Abstract
A new class of silicon (Si) nanohybrids is formed exploiting the Rayleigh instability experienced by Si nanowires (SiNWs) synthesized via inductively coupled plasma. These nanohybrids consist of three main categories of Si nanostructures: (i) core/shell silicon/silicon oxide nanowires (where the inner Si cores have diameters as small as 2–3 nm), (ii) sequences of almond-shaped silicon nanocrystals (SiNCs), having diameters in the range of 4–5 nm, connected by an ultrathin silicon nanowire (diameter of 1–2 nm) and embedded in a silica nanowire, and (iii) sequences of isolated spherical SiNCs (having diameters in the range of 4–7 nm) embedded in an otherwise continuous silica nanowire. The predominance of one morphology over the others can be tuned via post-synthesis thermal treatments, with a clear predominance of the spherical SiNC chain configuration after high-temperature annealing (1200 °C). It is demonstrated that the Rayleigh model describes very well the morphological transformations undergone by the Si core of the nanostructures when subject to the capillarity-related instability induced by the thermal annealing. More interestingly, we have been able, for the first time to our knowledge, to follow in situ the occurrence of Rayleigh instability in SiNWs leading to the breakage of their inner core and formation of smaller SiNCs. Finally, the optoelectronic properties of the Si nanohybrids, studied via photoluminescence measurements, have confirmed the occurrence of quantum confinement effects in the ultra-small SiNCs present in these new nanohybrids.
Highlights
Silicon (Si) nanostructures have been attracting a renewed interest in recent years because of their quantum confinement (QC)-induced visible light emission
Formation of Si nanohybrids By examining the structural and morphological characteristics of the as-grown inductively coupled plasma (ICP)-Si nanopowder, we found that three main families of Si nanostructures can be distinguished [5], as shown in figure 1: (i) cylindrical Si nanowires (SiNWs) presenting a rod-shaped Si nanocore, as depicted in figure 1(a); (ii) chaplet-like SiNWs featuring a chain of almond-shaped SiNCs connected by a very thin Si wire, as illustrated in figure 1(b); and (iii) SiNC chains consisting of a sequence of isolated spherical Si nanocrystals embedded in a continuous SiO2 cylinder, as those shown in figure 1(c)
Many concomitant phenomena occur during the complex ICP synthesis process, which makes it difficult to single out the effect of the temperature on the synthesized Si nanostructures
Summary
Silicon (Si) nanostructures have been attracting a renewed interest in recent years because of their quantum confinement (QC)-induced visible light emission. In the case of Si hybrid nanostructures, few papers have reported the occurrence of mixed SiNCs and SiNWs, where the SiNCs are generated via the periodic instability of the catalyst during the vapor–liquid–solid growth of SiNWs and promoted by the surface oxidization of the SiNWs, or are the result of renucleation and growth direction changes induced by the formation of unfavorable nuclei [11,12,13,14] Another alternative nanostructuring approach, based on the Plateau–Rayleigh assisted growth [15, 16], has recently demonstrated the possibility of in situ diameter modulation of SiNWs having initial core diameters of 100 nm [10].
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
