Enhancement of the core near-band-edge emission induced by an amorphous shell in coaxial one-dimensional nanostructure: the case of SiC/SiO₂core/shell self-organized nanowires

Abstract

We report the influence of the native amorphous SiO(2) shell on the cathodoluminescence emission of 3C-SiC/SiO(2) core/shell nanowires. A shell-induced enhancement of the SiC near-band-edge emission is observed and studied as a function of the silicon dioxide thickness. Since the diameter of the investigated SiC cores rules out any direct bandgap optical transitions due to confinement effects, this enhancement is ascribed to a carrier diffusion from the shell to the core, promoted by the alignment of the SiO(2) and SiC bands in a type I quantum well. An accurate correlation between the optical emission and structural and SiO(2)-SiC interface properties is also reported.

Porphyrin conjugated SiC/SiOx nanowires for X-ray-excited photodynamic therapy

“…The emission from bare NWs consists of a single large and unstructured peak centred at 523.5 nm, in excellent agreement with the near band-edge emission (NBE) of 3C-SiC12. The spectrum of the conjugated NWs clearly contains both contributions originating from the inorganic and organic components.…”

“…This nanosystem presents an optical emission spectrum12 which matches well the absorption bands of many organic photosensitizers and can be easily functionalized with inorganic crystals as well as with organic molecules1314.…”

Optical properties of hybrid T3Pyr/SiO2/3C-SiC nanowires

“…Figure 5 shows a typical zero-loss filtered image and a Z-contrast image, acquired on single NWs after HF etching of the sample in (1:3) aqueous solution for 60 s. As reported in a previous work [13], the etching acts selectively on silicon dioxide and allows the partial removal of the amorphous layer, leaving the core wrapped by the shell with a thickness ratio of about 1:1 compared to 1:5 of the as-grown sample [14]. This treatment is required for the TEM observation to enhance the diffraction contrast and improve the visibility of the inner core, allowing a study of its crystalline structure and defects.…”

“…In addition, recent works have demonstrated enhancement and possible tuning of the optical emission of silicon carbide NWs covered with native silicon dioxide amorphous shell [13,14]. This effect could be employed to improve the performances of sensors, based on the transduction of chemical reaction in optical emission, and also in possible in vivo application.…”

The Effect of Substrate Type on SiC Nanowire Orientation

“…3 Moreover, -SiC NWs with amorphous silicon dioxide wrapping layer are interesting for fundamental research and technological applications. [4][5] Many methods have been reported for the preparation of SiC NWs on silicon substrates using a catalyst, such as: i) chemical vapour deposition, included MOCVD, 6-10 ii) sputtering from a silicon carbide target, 11 iii) physical evaporation in vacuum of powdered commercial silicon carbide and Fe powder as catalyst, 12 * Author to whom correspondence should be addressed. iv) direct synthesis at high-temperature by reaction of different powders such as SiO, C, oxides and carbothermal reduction.…”