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Surface Chemistry Involved in Epitaxy of Graphene on 3C-SiC(111)/Si(111).

Abe S, Handa H, Takahashi R, Imaizumi K, Fukidome H, Suemitsu M - Nanoscale Res Lett (2010)

Bottom Line: Surface chemistry involved in the epitaxy of graphene by sublimating Si atoms from the surface of epitaxial 3C-SiC(111) thin films on Si(111) has been studied.The change in the surface composition during graphene epitaxy is monitored by in situ temperature-programmed desorption spectroscopy using deuterium as a probe (D(2)-TPD) and complementarily by ex situ Raman and C1s core-level spectroscopies.The surface of the 3C-SiC(111)/Si(111) is Si-terminated before the graphitization, and it becomes C-terminated via the formation of C-rich (6√3 × 6√3)R30° reconstruction as the graphitization proceeds, in a similar manner as the epitaxy of graphene on Si-terminated 6H-SiC(0001) proceeds.

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ABSTRACT
Surface chemistry involved in the epitaxy of graphene by sublimating Si atoms from the surface of epitaxial 3C-SiC(111) thin films on Si(111) has been studied. The change in the surface composition during graphene epitaxy is monitored by in situ temperature-programmed desorption spectroscopy using deuterium as a probe (D(2)-TPD) and complementarily by ex situ Raman and C1s core-level spectroscopies. The surface of the 3C-SiC(111)/Si(111) is Si-terminated before the graphitization, and it becomes C-terminated via the formation of C-rich (6√3 × 6√3)R30° reconstruction as the graphitization proceeds, in a similar manner as the epitaxy of graphene on Si-terminated 6H-SiC(0001) proceeds.

No MeSH data available.


Cls core-level spectra of SiC thin film on Si, after annealing at (i) 1,273 K (sample B), (ii) 1,423 K (Sample C), (iii) 1,523 K (sample D) annealing, respectively
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Figure 3: Cls core-level spectra of SiC thin film on Si, after annealing at (i) 1,273 K (sample B), (ii) 1,423 K (Sample C), (iii) 1,523 K (sample D) annealing, respectively

Mentions: On the (6√3 × 6√3)R30°-reconstructed 3C-SiC(111)/Si(111) (Sample C), the TPD spectrum consists mainly of Dx-Si(C). Here, x = 1 stands for the peak at 960 K and x = 2 for the peak at 850 K [10]. The peaks due to Dx-Si (500–800 K) almost disappear. It has been demonstrated in a previous report that the adsorption of hydrogen atoms onto the (6√3 × 6√3)R30°-reconstructed SiC surface breaks the bondings between the reconstructed layer and the SiC interface, so that the surface carbon atoms in the layer are converted into graphene layer, and the SiC interface is terminated with hydrogen [11,12]. The main peak at 960 K is thus attributable to the deuterium desorption from D-terminated SiC interface that results from the breakage of the bonds between the (6√3 × 6√3)R30°-reconstructed layer and the underneath SiC surface. Small features appear in the temperature range of 1,100–1,400 K. They are due to desorption of deuterium atoms bonded on sp2-bonded carbon atoms by D-exposure [13,14]. The appearance of these peaks is in agreement with the presence of the (6√3 × 6√3)R30°-reconstructed layer because the reconstructed layer mainly consists of sp2-bonded atoms, and part of the carbon atoms are covalently bonded with the SiC surface [15]. This D2-TPD result is in good agreement with the Raman spectrum of the reconstructed layer. The appearance of the broad G band (~1,600 cm−1) indicates the formation of the cluster of sp2-bonded carbon atoms, i.e., nanographene. The appearance of the D band (~1,350 cm−1) and the absence of the G′ band (~2,700 cm−1), however, indicate a low degree of the crystallinity of the sp2-bonded network of the carbon atoms. C1s core-level spectrum of the (6√3 × 6√3)R30°-reconstructed layer (Fig. 3(i)) actually supports the idea. In the core-level spectrum, the surface components S1 (~285.2 eV) and S2 (~284.0 eV) appear as well as the component due to the bulk of the SiC thin film (~283.0 eV). S1 and S2 are due to the carbon atoms connected with the SiC surface and the sp2-bonded carbon atoms, respectively, in the (6√3 × 6√3)R30°-reconstructed layer [15]. The intensity ratio of S1 and S2 peak is 2, as that of the spectrum of (6√3 × 6√3)R30°-reconstructed layer on 6H-SiC(0001). Thus, the 3C-SiC(111)/Si(111) surface is proven to become C rich and (6√3 × 6√3)R30° reconstructed by annealing the Si-terminated (√3 × √3)R30°-reconstructed surface [15]. This change in the surface chemistry of 3C-SiC(111)/Si(111) is quite similar to that of 6H-SiC(0001) [3,4,15].


Surface Chemistry Involved in Epitaxy of Graphene on 3C-SiC(111)/Si(111).

Abe S, Handa H, Takahashi R, Imaizumi K, Fukidome H, Suemitsu M - Nanoscale Res Lett (2010)

Cls core-level spectra of SiC thin film on Si, after annealing at (i) 1,273 K (sample B), (ii) 1,423 K (Sample C), (iii) 1,523 K (sample D) annealing, respectively
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Related In: Results  -  Collection

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Figure 3: Cls core-level spectra of SiC thin film on Si, after annealing at (i) 1,273 K (sample B), (ii) 1,423 K (Sample C), (iii) 1,523 K (sample D) annealing, respectively
Mentions: On the (6√3 × 6√3)R30°-reconstructed 3C-SiC(111)/Si(111) (Sample C), the TPD spectrum consists mainly of Dx-Si(C). Here, x = 1 stands for the peak at 960 K and x = 2 for the peak at 850 K [10]. The peaks due to Dx-Si (500–800 K) almost disappear. It has been demonstrated in a previous report that the adsorption of hydrogen atoms onto the (6√3 × 6√3)R30°-reconstructed SiC surface breaks the bondings between the reconstructed layer and the SiC interface, so that the surface carbon atoms in the layer are converted into graphene layer, and the SiC interface is terminated with hydrogen [11,12]. The main peak at 960 K is thus attributable to the deuterium desorption from D-terminated SiC interface that results from the breakage of the bonds between the (6√3 × 6√3)R30°-reconstructed layer and the underneath SiC surface. Small features appear in the temperature range of 1,100–1,400 K. They are due to desorption of deuterium atoms bonded on sp2-bonded carbon atoms by D-exposure [13,14]. The appearance of these peaks is in agreement with the presence of the (6√3 × 6√3)R30°-reconstructed layer because the reconstructed layer mainly consists of sp2-bonded atoms, and part of the carbon atoms are covalently bonded with the SiC surface [15]. This D2-TPD result is in good agreement with the Raman spectrum of the reconstructed layer. The appearance of the broad G band (~1,600 cm−1) indicates the formation of the cluster of sp2-bonded carbon atoms, i.e., nanographene. The appearance of the D band (~1,350 cm−1) and the absence of the G′ band (~2,700 cm−1), however, indicate a low degree of the crystallinity of the sp2-bonded network of the carbon atoms. C1s core-level spectrum of the (6√3 × 6√3)R30°-reconstructed layer (Fig. 3(i)) actually supports the idea. In the core-level spectrum, the surface components S1 (~285.2 eV) and S2 (~284.0 eV) appear as well as the component due to the bulk of the SiC thin film (~283.0 eV). S1 and S2 are due to the carbon atoms connected with the SiC surface and the sp2-bonded carbon atoms, respectively, in the (6√3 × 6√3)R30°-reconstructed layer [15]. The intensity ratio of S1 and S2 peak is 2, as that of the spectrum of (6√3 × 6√3)R30°-reconstructed layer on 6H-SiC(0001). Thus, the 3C-SiC(111)/Si(111) surface is proven to become C rich and (6√3 × 6√3)R30° reconstructed by annealing the Si-terminated (√3 × √3)R30°-reconstructed surface [15]. This change in the surface chemistry of 3C-SiC(111)/Si(111) is quite similar to that of 6H-SiC(0001) [3,4,15].

Bottom Line: Surface chemistry involved in the epitaxy of graphene by sublimating Si atoms from the surface of epitaxial 3C-SiC(111) thin films on Si(111) has been studied.The change in the surface composition during graphene epitaxy is monitored by in situ temperature-programmed desorption spectroscopy using deuterium as a probe (D(2)-TPD) and complementarily by ex situ Raman and C1s core-level spectroscopies.The surface of the 3C-SiC(111)/Si(111) is Si-terminated before the graphitization, and it becomes C-terminated via the formation of C-rich (6√3 × 6√3)R30° reconstruction as the graphitization proceeds, in a similar manner as the epitaxy of graphene on Si-terminated 6H-SiC(0001) proceeds.

View Article: PubMed Central - HTML - PubMed

ABSTRACT
Surface chemistry involved in the epitaxy of graphene by sublimating Si atoms from the surface of epitaxial 3C-SiC(111) thin films on Si(111) has been studied. The change in the surface composition during graphene epitaxy is monitored by in situ temperature-programmed desorption spectroscopy using deuterium as a probe (D(2)-TPD) and complementarily by ex situ Raman and C1s core-level spectroscopies. The surface of the 3C-SiC(111)/Si(111) is Si-terminated before the graphitization, and it becomes C-terminated via the formation of C-rich (6√3 × 6√3)R30° reconstruction as the graphitization proceeds, in a similar manner as the epitaxy of graphene on Si-terminated 6H-SiC(0001) proceeds.

No MeSH data available.