Direct Growth and Photoluminescence of SiOx Nanowires and Aligned Nanocakes by Simple Carbothermal Evaporation

Abstract

The growth of SiO x nanowires and nanocakes on an Au-coated n-type-Silicon (100) substrate was achieved via carbothermal evaporation. The effects of the Au layer thickness and the rapid heating rate on the morphology of obtained SiO x nanowires were investigated. A broad emission band from 290 to 600 nm was observed in the photoluminescence (PL) spectrum of these nanowires. There are four PL peaks: one blue emission peak 485 nm (2.56 eV) two green bands centered at 502 nm (2.47 eV) and 524 nm (2.37 eV) for nanocakes and one ultraviolet emission peak at 350 nm (3.54 eV) and a hemisphere curve over the bluish green area taken for SiO x nanowires. These emissions may be related to the various oxygen defects and twofold coordinated silicon lone pair centers.

Microstructure and Optical Properties of Oxygen-Annealed c-Si/a-SiO2 Core–Shell Silicon Nanowires

“…The main intrinsic defects (oxygen vacancies) of as-grown Si-NWs can be reduced by oxygen annealing. The green emission in Si-NWs is known to be attributed to the neutral vacancy in which the radiative recombination of a photon-generated hole with an electron occupying the neutral vacancy is involved in the process. , …”

“…Some important points are addressed as follows: The main intrinsic defects (oxygen vacancies) of as-grown Si-NWs can be reduced by oxygen annealing. The green emission in Si-NWs is known to be attributed to the neutral vacancy in which the radiative recombination of a photon-generated hole with an electron occupying the neutral vacancy is involved in the process. , The hydrogen is replaced by oxygen from the surface and the interface of the Si-NWs during oxygen annealing. The oxygen point defects in Si-NWs could easily replace O to generate deep level. , …”

Ultraviolet emission of amorphous SiO2+x nanowires with connected bead-chain morphology

“…Among various SiO x morphologies, nanowire is the main one which has been successfully fabricated via many routes, such as chemical vapor deposition, 10,11 laser ablation, 12 thermal evaporation, 13,14 hydrothermal synthesis, 15 etc. Other morphologies, such as nanobelts, 16 nanotubes, 17 nanolanterns 13 or nanocakes 14 have also been successfully synthesized.…”

“…Among the metal catalysts, Au is preferred to be used for SiO x nanowires growth, as it has low eutectic temperature with silicon (T z 363 C). 6,14 Other metal catalysts, such as Sn, 11 Fe, 19 Ge 20 and Ni 21 have been reported for the growth of SiO x nanomaterials. Except for VLS mechanism, solid-liquid-solid (SLS) mechanism is also proposed by Wang et al 22 In this work, a novel type of SiO 2+x nanowires with connected bead-chain morphology were successfully fabricated via CVD method by using Au as the catalyst.…”