Birth of silicon nanowires covered with protective insulating blanket
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Research Letter
Birth of silicon nanowires covered with protective insulating blanket Krishna Nama Manjunatha and Shashi Paul, Emerging Technologies Research Center, De Montfort University, The Gateway, Leicester LE18BH, UK Address all correspondence to Shashi Paul at [email protected] (Received 27 July 2017; accepted 5 September 2017)
Abstract Core–shell silicon–silicon oxide nanowires are synthesized at low temperatures using inorganic and organic compounds of a tin as a catalyst. In situ simultaneous one-dimensional growth of pristine silicon nanowires (SiNWs) using alloy catalyst is reported here. Such a development process generates a high-quality SiNW that is not determined by other atomic species in the plasma. A possible growth model is discussed to understand the synchronized precipitation of a SiNW core and an oxide shell. Nanowires grown here eliminate the additional fabrication steps to deposit anticipated oxide shell that is achieved by precipitation from the same catalyst that precipitates core nanowires.
Silicon (Si) nanostructures are possible to be produced as zero-dimensional nanoparticles (NPs), one-dimensional (1D) nanowires (NWs), and two-dimensional thin films. Si-based nanostructures exhibit better optical, electrical, and mechanical properties compared with bulk Si. Due to the fascinating properties exhibited by nanomaterials, they have gained interest in nanoscale electronic devices, mesoscopic research, and miniaturization of devices, while enhancing efficiency and reducing costs. Silicon NWs (SiNWs) have gained their importance in photovoltaics, memory devices, battery applications, photo sensors, biosensors, and many more. Similar to realization of SiNWs for many electronic applications, Si–SiOx core–shell NWs have gained interest in transistors, batteries, and solar cells.[1,2] SiOx wrapped SiNW facilitates its use as a cylindrical dielectric layer with a wrapped metal gate that exhibits a reduced consumption of power and a better coupling of gate as compared with planar field effect transistors. The enhancement in the field emission properties of the SiNWs is observed due to the positive electron affinity of 0.6–0.8 eV in Si–SiOx core–shell NWs.[3] Si–SiOx core–shell NWs have gained tremendous interest in emerging electronics such as lithium-ion batteries, where the capacity contribution is achieved from core Si and amorphous SiOx accommodates large volume variation during the charge and discharge cycles of a battery. Recently, this was demonstrated by growing 10 nm Si core covered by 50 nm SiO[x1] and further investigated by altering dimensions of SiOx shell.[2] Luminescence applications signifying better efficiency with SiOx shell layer compared with hydrogen-passivated NWs.[4] SiOx shell acts as an effective passivation layer for low-velocity recombination, enhances the electron transport in SiNWs coated with SiOx due to negative dipole of Si oxide and demonstrating an enhancement in the efficiency of the solar cell.[5] By measuring the surface
dipole energy about 0.2 eV produced by SiO c
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