Order and disorder at the C-face of SiC: A hybrid surface reconstruction

Machado-Charry, Eduardo; González, César; Dappe, Yannick J.; Magaud, Laurence; Mousseau, Normand; Pochet, Pascal

doi:10.1063/1.5143010

Cited by 1 publication

(1 citation statement)

References 22 publications

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“…On the other hand, the sp 2 -carbon at the SiC surface can improve the specific contact resistance of the SiC/metal interface . The surface of SiC accommodates diverse surface reconstruction and termination with corresponding defects such as bridge and triple-bonded C/Si dimers, which generate fruitful surface states in the band gap. − Hence, the SiC surface has attracted great interest. , As the dimension of the semiconductor SiC is reduced to the nanoscale, its surface structure becomes even more complex, the dangling bonds of the active carbon and silicon atoms of the freshly prepared SiC quantum dots (QDs) can readily be passivated by oxygen and hydrogen atoms to form quite fruitful bonding structures. − The resultant surface states in the band gap can actively participate in the photon absorption and emission processes. − The whole surface passivation layer becomes a two-dimensional quantum system, which in combination with quantum confinement − and the intentionally created interior point defects − determines the photodynamics ,− and charge transport properties of the SiC QDs. Therefore, understanding the surface structures and characteristics of the SiC QDs is critical for realizing their better applications in biological labeling, − solid-state lighting, − and quantum spintronics. − Our previous study indicates that the CO bonds on the SiC QD surface generate surface-localized orbitals and contribute to the blue fluorescence; however, the role of the silicon–oxygen bonds in fluorescence of the SiC QDs remains unclear.…”

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confidence: 99%

Core and Surface Electronic States and Phonon Modes in SiC Quantum Dots Studied by Optical Spectroscopy and Hybrid TDDFT

Liu

Liang

et al. 2021

J. Phys. Chem. C

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The surface of the SiC quantum dot (QD) is a complex two-dimensional system that comprises fruitful surface reconstruction and passivation which affect its chemistry and photophysics. Here, we report the novel yellow fluorescence (2.19 eV) of the colloidal SiC QDs in the quantum confinement regime, which decays much slowly (lifetime > 70 ns) compared with the previously observed blue-green fluorescence (<15 ns). The semi-empirical and time-dependent density functional theory calculations reveal that it originates from the trapped surface states at the SiO bond, whose energy levels lie in the forbidden gap of the SiC QD. There exists multiple splitting of the transverse and longitudinal optical phonon modes of the SiC QD, and there is an infrared active fingerprint surface mode belonging to the SiO bond. The calculations agree well with the experiments. These findings highly improve our understanding of the surface properties of the SiC QDs.

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