6H-SiC and 3C-SiC single crystals were simultaneously irradiated at room temperature with 100 keV Fe ions at fluences up to 4 × 1014 cm−2 (∼0.7 dpa), i.e. up to amorphization. The disordering behaviour of both polytypes has been investigated by means of Rutherford backscattering spectrometry in the channelling mode and synchrotron x-ray diffraction. For the first time, it is experimentally demonstrated that the general damage build-up is similar in both polytypes. At low dose, irradiation induces the formation of small interstitial-type defects. With increasing dose, amorphous domains start to form at the expense of the defective crystalline regions. Full amorphization of the irradiated layer is achieved at the same dose (∼0.45 dpa) for both polytypes. It is also shown that the interstitial-type defects formed during the first irradiation stage induce a tensile elastic strain (up to ∼4.0%) with which is associated an elastic energy. It is conjectured that this stored energy destabilizes the current defective microstructure observed at low dose and stimulates the formation of the amorphous nanostructures at higher dose. Finally, the disorder accumulation has been successfully reproduced with two models (namely multi-step damage accumulation and direct-impact/defect-stimulated). Results obtained from this modelling are compared and discussed in the light of experimental data.
In recent times, trilayer graphene has attracted wide attention owing to its stacking and electric-field-dependent electronic properties. However, a direct and well-resolved experimental visualization of its band structure has not yet been reported. In this paper, we present angle-resolved photoemission spectroscopy data which show with high resolution the electronic band structure of trilayer graphene obtained on α-SiC(0001) and β-SiC(111) via hydrogen intercalation. Electronic bands obtained from tight-binding calculations are fitted to the experimental data to extract the interatomic hopping parameters for Bernal and rhombohedral stacked trilayers. Low-energy electron microscopy measurements demonstrate that the trilayer domains extend over areas of tens of square micrometers, suggesting the feasibility of exploiting this material in electronic and photonic devices. Furthermore, our results suggest that, on SiC substrates, the occurrence of a rhombohedral stacked trilayer is significantly higher than in natural bulk graphite.
The healing effect of intense electronic energy deposition arising during swift heavy ion (SHI) irradiation is demonstrated in the case of 3C-SiC damaged by nuclear energy deposition. Experimental (ion channeling experiments) and computational (molecular dynamics simulations) studies provide consistent indications of disorder decrease after SHI irradiation. Furthermore, both methods establish that SHI-induced recrystallization takes place at amorphous-crystalline interfaces. The recovery process is unambiguously accounted for by the thermal spike phenomenon.
Silicon carbide (SiC) is emerging rapidly in novel photonic applications thanks to its unique photonic properties facilitated by the advances of nanotechnologies such as nanofabrication and nanofilm transfer. This review paper will start with the introduction of exceptional optical properties of silicon carbide. Then, a key structure, i.e., silicon carbide on insulator stack (SiCOI), is discussed which lays solid fundament for tight light confinement and strong light-SiC interaction in high quality factor and low volume optical cavities. As examples, microring resonator, microdisk and photonic crystal cavities are summarized in terms of quality (Q) factor, volume and polytypes. A main challenge for SiC photonic application is complementary metal-oxide-semiconductor (CMOS) compatibility and low-loss material growth. The state-of-the-art SiC with different polytypes and growth methods are reviewed and a roadmap for the loss reduction is predicted for photonic applications. Combining the fact that SiC possesses many different color centers with the SiCOI platform, SiC is also deemed to be a very competitive platform for future quantum photonic integrated circuit applications. Its perspectives and potential impacts are included at the end of this review paper.
Large scale, homogeneous quasi-free standing monolayer graphene is obtained on cubic silicon carbide, i.e., the 3C-SiC(111) surface, which represents an appealing and cost effective platform for graphene growth. The quasi-free monolayer is produced by intercalation of hydrogen under the interfacial, (63×63)R30 °-reconstructed carbon layer. After intercalation, angle resolved photoemission spectroscopy reveals sharp linear π-bands. The decoupling of graphene from the substrate is identified by x-ray photoemission spectroscopy and low energy electron diffraction. Atomic force microscopy and low energy electron microscopy demonstrate that homogeneous monolayer domains extend over areas of hundreds of square-micrometers.