A comparative DFT study of electronic properties of 2H-, 4H- and 6H-SiC(0001) and SiC(000 \bar{1} ) clean surfaces: significance of the surface Stark effect

Sołtys, Jakub; Piechota, Jacek; Łopuszyński, Michał; Krukowski, S.

doi:10.1088/1367-2630/12/4/043024

Cited by 30 publications

(20 citation statements)

References 35 publications

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“…The 4H-SiC crystal was represented by a hexagonal supercell containing eight atoms that was repeated periodically in space. The calculated lattice parameters for 4H-SiC polytype (a = 3.113 Å, c = 10.205 Å) are in good agreement with experimental data (a = 3.073 Å, c = 10.053 Å [12]) and with results of recent plane--wave-basis calculations [13] performed by applying the projector-augmented wave method and the GGA-PBE functional. The determined lattice parameters were applied to construct slabs of 12 SiC double-layers representing the (0001) and (0001) surfaces of the 4H-SiC crystal, terminated with Si and C atoms, respectively.…”

Section: Methodssupporting

confidence: 85%

“…The dangling bonds on the bottom layer atoms of the slabs were saturated by hydrogen atoms. The slabs of such thickness which were separated from their periodic replicas in neighbouring cells by a vacuum region of ≈ 20 Å proved to be sucient for reproducing surface properties [13]. The atomic positions of the four topmost double SiC layers of the slab, and of the terminating H atoms on the backside were relaxed until forces acting on atoms converged to less than 0.02 eV/Å.…”

Section: Methodsmentioning

confidence: 99%

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Ab Initio Studies of Al and Ga Adsorption on 4H-SiC{0001} Surfaces

2012

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Changes in the atomic and electronic structure of Si-and C-terminated 4H-SiC{0001} surfaces resulting from aluminium and gallium adsorption have been studied within density functional theory framework. Al and Ga coverages ranging from a submonolayer to one monolayer were considered. Our results show that Al binds more strongly to both surfaces than Ga. The binding is stronger to the C-terminated surface for both metals. The sites occupied by Al and Ga atoms at 1 monolayer are dierent and it is due to a dierent charge transfer from metal to the substrate.

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Section: Methodssupporting

confidence: 85%

Section: Methodsmentioning

confidence: 99%

Ab Initio Studies of Al and Ga Adsorption on 4H-SiC{0001} Surfaces

2012

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“…A necessary procedure should therefore use the projected density of states (P-DOS) to identify how the field affects the energy of states, i.e. identify the surface states Stark effect (SSSE) [15][16][17]. In order to obtain the correct alignment of the bands, it is necessary to remove SSSE, i.e.…”

Section: Discussionmentioning

confidence: 99%

“…It was proven that by proper manipulation of the surface termination atoms, either their location or their charge, the average electric field within the slab may be changed [12][13][14]. The model was formulated and applied in the studies of GaN(0001) [12][13][14][15][16] and SiC(0001) and SiC(0001) polar surfaces [17]. Naturally, the change of the energies of the quantum states by the field at the surface was denoted as the surface states Stark effect SSSE [13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Foundations of ab initio simulations of electric charges and fields at semiconductor surfaces within slab models

Krukowski

Kempisty

Strąk

2013

Journal of Applied Physics

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Semiconductor surfaces were divided into charge categories, i.e. surface acceptor, donor and neutral ones that are suitable for simulations of their properties within a slab model. The potential profiles, close to the charged surface states, accounting for explicit dependence of the point defects energy, were obtained. A termination charge slab model was formulated and analyzed proving that two control parameters of slab simulations exist: the slope and curvature of electric potential profiles which can be translated into a surface and volumetric charge density. The procedures of slab model parameter control 2 are described and presented using examples of the DFT simulations of GaN and SiC surfaces showing the potential profiles, linear or curved, depending on the band charge within the slab. It was also demonstrated that the field at the surface may affect some surface properties in a considerable degree proving that verification of this dependence is obligatory for a precise simulation of the properties of semiconductor surfaces.

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“…The 4H-SiC{0001} superlattice was constructed using 8 bilayers of Si-C which was sufficient to avoid a quantum overlap of the termination and real surface quantum states. 42 Two top SiC layers were relaxed using the conjugate gradient algorithm.…”

Section: Dft Calculation Methodsmentioning

confidence: 99%

Role of structure of C-terminated4H-SiC(0001¯) surface in growth of graphene layers: Transmission electron microscopy and density functional theory studies

et al. 2012

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Principal structural defects in graphene layers, synthesized on a carbon-terminated face, i.e. the SiC(0001 ) face of a 4H-SiC substrate, are investigated using microscopic methods.Results of high-resolution transmission electron microscopy (HRTEM) reveal their atomic arrangement. Mechanism of such defects creation, directly related to the underlying crystallographic structure of the SiC substrate, is elucidated. The connection between the 4H-SiC(0001 ) surface morphology, including the presence of the single atomic steps, the sequences of atomic steps, and also the macrosteps, and the corresponding emergence of planar defective structure (discontinuities of carbon layers and wrinkles) is revealed. It is shown that disappearance of the multistep island leads to the creation of wrinkles in the graphene layers. The density functional theory (DFT) calculation results show that the diffusion of both silicon and carbon atoms is possible on a Si-terminated SiC surface at a high temperature close to 1600°C. The creation of buffer layer at the Si-terminated surface effectively blocks horizontal diffusion, preventing growth of thick graphene layer at this face.At the carbon terminated SiC surface, the buffer layer is absent leaving space for effective horizontal diffusion of both silicon and carbon atoms. DFT results show that excess carbon atoms converts a topmost carbon layer to sp 2 bonded configuration, liberating Si atoms in a) Electronic mail: jolanta.borysiuk@fuw.edu.pl 2 barrierless process. The silicon atoms escape through the channels created at the bending layers defects, while the carbon atoms are incorporated into the growing graphene layers.These results explain growth of thick graphene underneath existing graphene cover and also the creation of the principal defects at the C-terminated SiC(0001) surface.

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A comparative DFT study of electronic properties of 2H-, 4H- and 6H-SiC(0001) and SiC(000 \bar{1} ) clean surfaces: significance of the surface Stark effect

Cited by 30 publications

References 35 publications

Ab Initio Studies of Al and Ga Adsorption on 4H-SiC{0001} Surfaces

Ab Initio Studies of Al and Ga Adsorption on 4H-SiC{0001} Surfaces

Foundations of ab initio simulations of electric charges and fields at semiconductor surfaces within slab models

Role of structure of C-terminated4H-SiC(0001¯) surface in growth of graphene layers: Transmission electron microscopy and density functional theory studies

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