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Grassy Silica Nanoribbons and Strong Blue Luminescence

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ABSTRACT

Silicon dioxide (SiO2) is one of the key materials in many modern technological applications such as in metal oxide semiconductor transistors, photovoltaic solar cells, pollution removal, and biomedicine. We report the accidental discovery of free-standing grassy silica nanoribbons directly grown on SiO2/Si platform which is commonly used for field-effect transistors fabrication without other precursor. We investigate the formation mechanism of this novel silica nanostructure that has not been previously documented. The silica nanoribbons are flexible and can be manipulated by electron-beam. The silica nanoribbons exhibit strong blue emission at about 467 nm, together with UV and red emissions as investigated by cathodoluminescence technique. The origins of the luminescence are attributed to various defects in the silica nanoribbons; and the intensity change of the blue emission and green emission at about 550 nm is discussed in the frame of the defect density. Our study may lead to rational design of the new silica-based materials for a wide range of applications.

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CL characteristics of silica nanoribbons.(a) SEM image showing the positions where the CL spectra were acquired in (b) and emission maps in (e,f). (b) CL spectra acquired at different positions. (c) Schematical illustration of an OVC and a NBOHC, neutral oxygen vacancy, and Si hexamer ring. (d) Blue band map corresponding to (a). (e) Green band map corresponding to (a).
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f4: CL characteristics of silica nanoribbons.(a) SEM image showing the positions where the CL spectra were acquired in (b) and emission maps in (e,f). (b) CL spectra acquired at different positions. (c) Schematical illustration of an OVC and a NBOHC, neutral oxygen vacancy, and Si hexamer ring. (d) Blue band map corresponding to (a). (e) Green band map corresponding to (a).

Mentions: Defects in SiO2 exert significant influences on its properties such as dielectric performance and luminescence. The defect structure of SiO2 is extremely sensitive to ionizing radiation3334. Several kinds of defects in amorphous SiO2 are optically active and can be studied by luminescence spectroscopy. We investigated the defect-induced luminescence properties of the grassy silica nanoribbons by CL spectroscopy, which is a frequently used technique for high spatial resolution and high-sensitivity detection of defect centers in materials. Figure 4 displays the CL characterization results. All the CL spectra (#2–#9 in Fig. 4a,b) acquired from the different sample locations of nanoribbons possess luminescence features at around 285 nm (4.35 eV, UV band), 467 nm (2.60 eV, blue band), 550 nm (2.25 eV, green band), and 645 nm (1.92 eV, red band)33. No blue emission can be detected from the substrate (#1). These luminescent bands are common in silica and the specific luminescence centers related to them have been well documented35363738, originating from local atomic rearrangement that deviates from the SiO4 tetrahedra expected for a perfect silica matrix. The red emission band ascribed to the nonbridging oxygen hole centers (NBOHCs)3940 (see Fig. 4c). The UV emission band can be originated from particular kinds of oxygen vacancy centers (OVCs) such as the discoordinated Si or neutral oxygen vacancy (Fig. 4c)3537.


Grassy Silica Nanoribbons and Strong Blue Luminescence
CL characteristics of silica nanoribbons.(a) SEM image showing the positions where the CL spectra were acquired in (b) and emission maps in (e,f). (b) CL spectra acquired at different positions. (c) Schematical illustration of an OVC and a NBOHC, neutral oxygen vacancy, and Si hexamer ring. (d) Blue band map corresponding to (a). (e) Green band map corresponding to (a).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5035931&req=5

f4: CL characteristics of silica nanoribbons.(a) SEM image showing the positions where the CL spectra were acquired in (b) and emission maps in (e,f). (b) CL spectra acquired at different positions. (c) Schematical illustration of an OVC and a NBOHC, neutral oxygen vacancy, and Si hexamer ring. (d) Blue band map corresponding to (a). (e) Green band map corresponding to (a).
Mentions: Defects in SiO2 exert significant influences on its properties such as dielectric performance and luminescence. The defect structure of SiO2 is extremely sensitive to ionizing radiation3334. Several kinds of defects in amorphous SiO2 are optically active and can be studied by luminescence spectroscopy. We investigated the defect-induced luminescence properties of the grassy silica nanoribbons by CL spectroscopy, which is a frequently used technique for high spatial resolution and high-sensitivity detection of defect centers in materials. Figure 4 displays the CL characterization results. All the CL spectra (#2–#9 in Fig. 4a,b) acquired from the different sample locations of nanoribbons possess luminescence features at around 285 nm (4.35 eV, UV band), 467 nm (2.60 eV, blue band), 550 nm (2.25 eV, green band), and 645 nm (1.92 eV, red band)33. No blue emission can be detected from the substrate (#1). These luminescent bands are common in silica and the specific luminescence centers related to them have been well documented35363738, originating from local atomic rearrangement that deviates from the SiO4 tetrahedra expected for a perfect silica matrix. The red emission band ascribed to the nonbridging oxygen hole centers (NBOHCs)3940 (see Fig. 4c). The UV emission band can be originated from particular kinds of oxygen vacancy centers (OVCs) such as the discoordinated Si or neutral oxygen vacancy (Fig. 4c)3537.

View Article: PubMed Central - PubMed

ABSTRACT

Silicon dioxide (SiO2) is one of the key materials in many modern technological applications such as in metal oxide semiconductor transistors, photovoltaic solar cells, pollution removal, and biomedicine. We report the accidental discovery of free-standing grassy silica nanoribbons directly grown on SiO2/Si platform which is commonly used for field-effect transistors fabrication without other precursor. We investigate the formation mechanism of this novel silica nanostructure that has not been previously documented. The silica nanoribbons are flexible and can be manipulated by electron-beam. The silica nanoribbons exhibit strong blue emission at about 467 nm, together with UV and red emissions as investigated by cathodoluminescence technique. The origins of the luminescence are attributed to various defects in the silica nanoribbons; and the intensity change of the blue emission and green emission at about 550 nm is discussed in the frame of the defect density. Our study may lead to rational design of the new silica-based materials for a wide range of applications.

No MeSH data available.


Related in: MedlinePlus