Abstract
In light of the recent publication of a report on the preparation of crystalline silicon carbide nanowires (NWs) covered with silicon oxide (SiC/SiO2) core–shell nanowires at low temperature, this study uses first-principles calculations based on the related transmission electron microscope micrographs to study hydrogen-passivated 3C-, 2H-, 4H-, and 6H-SiC NWs and their combinations. The aim is to examine charge transfers at the 2H/3C and the 2H/4H/3C interfaces in case there is no limit to periodicity. The orbital wavefunctions in the calculated interfaces exhibited changes from valence band maximum to conduction band minimum. The results of the photoluminescence spectrum showed a peak at a wavelength of 392 nm in terms of the intensity of emission, where this has been expected for such microstructures. Zhang et al. claimed that the source of this peak lies in nanoscale 6H-SiC layers, but our simulations based on experimental measurements indicate that it likely originates in 3C-SiC nanowires with a diameter of 1.5 nm.
Highlights
The Brillouin zone (BZ) integral was based on the Gaussian smearing method,25,26 where the width of the smearing was set to 0.05 eV, and a Γ-centered 1 × 1 × 5 k-mesh and a plane-wave cutoff energy of
The bandgap in this case was 2.4 eV as the calculated interfacial structure was based on bulk silicon carbide (SiC), which is different from NWs, and there was no quantum confinement effect
SiCNWs were created by chemical vapor deposition, and their transmission electron microscope (TEM) micrographs clearly presented structures of ∼1.5 nm 3C-SiC, ∼1 nm 2H-SiC, ∼1 nm 4H-SiC, and ∼1.5 nm 6HSiC
Summary
Scitation.org/journal/adv where the peak appeared at 378 nm in the photoluminescence (PL) spectrum. Due to the existence of stacking faults within 3C-SiC, the defects have different structures, such as 2H-, 4H-, and 6H-like nanoscale layers. Certain types of stacking faults in 4H- and 6H-SiC can create very clear quantum well-like structures.. Consider a 3C-like nano-scaled layer; there is a split-off band below the conduction band minimum (CBM), which is strongly localized around the stacking fault. Due to the offset in the conduction band between structures, the electrons are confined to the local lower conduction band near the thin cubic region. It eventually forms a quantum well and confines the electrons to layers of the stacking fault. The interfacial calculations indicate that the charge will be transferred from the stacking faults (SFs) to the inside of the nanosegment as the energy increases
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