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Nanoscale characterization of electrical transport at metal/3C-SiC interfaces.

Eriksson J, Roccaforte F, Reshanov S, Leone S, Giannazzo F, Lonigro R, Fiorenza P, Raineri V - Nanoscale Res Lett (2011)

Bottom Line: In this case, annealing at 500°C resulted in a reduction of the leakage current and an increase of the Schottky barrier height (from 0.77 to 1.12 eV).A structural analysis of the reaction zone carried out by transmission electron microscopy [TEM] and X-ray diffraction showed that the improved electrical properties can be attributed to a consumption of the surface layer of SiC due to silicide (Pt2Si) formation.The degradation of Schottky characteristics at higher temperatures (up to 900°C) could be ascribed to the out-diffusion and aggregation of carbon into clusters, observed by TEM analysis.

View Article: PubMed Central - HTML - PubMed

Affiliation: CNR-IMM, Strada VIII n, 5, Zona Industriale, 95121, Catania, Italy. jens.eriksson@imm.cnr.it.

ABSTRACT
In this work, the transport properties of metal/3C-SiC interfaces were monitored employing a nanoscale characterization approach in combination with conventional electrical measurements. In particular, using conductive atomic force microscopy allowed demonstrating that the stacking fault is the most pervasive, electrically active extended defect at 3C-SiC(111) surfaces, and it can be electrically passivated by an ultraviolet irradiation treatment. For the Au/3C-SiC Schottky interface, a contact area dependence of the Schottky barrier height (ΦB) was found even after this passivation, indicating that there are still some electrically active defects at the interface. Improved electrical properties were observed in the case of the Pt/3C-SiC system. In this case, annealing at 500°C resulted in a reduction of the leakage current and an increase of the Schottky barrier height (from 0.77 to 1.12 eV). A structural analysis of the reaction zone carried out by transmission electron microscopy [TEM] and X-ray diffraction showed that the improved electrical properties can be attributed to a consumption of the surface layer of SiC due to silicide (Pt2Si) formation. The degradation of Schottky characteristics at higher temperatures (up to 900°C) could be ascribed to the out-diffusion and aggregation of carbon into clusters, observed by TEM analysis.

No MeSH data available.


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Morphology of the SiC surface and current map of an adjacent Pt contact. AFM morphology of the 3C-SiC(001) surface (a) and C-AFM current map determined at a tip bias of −5 V on an adjacent Pt contact after annealing at 500°C (b).
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Figure 3: Morphology of the SiC surface and current map of an adjacent Pt contact. AFM morphology of the 3C-SiC(001) surface (a) and C-AFM current map determined at a tip bias of −5 V on an adjacent Pt contact after annealing at 500°C (b).

Mentions: While XRD coupled with TEM analysis (see Figure 2) showed that all the Pt have been converted into the stable Pt2Si phase already at 500°C, higher temperature annealing gives rise to increased localized high leakage current areas at the contact interface. Figure 3a shows the morphology of the SiC surface where the large vertical lines are due to several stacking faults bunching together during the growth of the 3C-SiC substrate. Comparing Figure 3a with the current map of an adjacent Pt contact (Figure 3b) determined in the same sample orientation, it is clear that the localized leakage spots occur preferentially along the direction of stacking faults. The total area that is covered by these leaky spots was determined from current maps measured after each annealing temperature and increases from 12% at 500°C to 28% and 55% after annealing at 700°C and 900°C, respectively. These leakage spots suggest a Schottky barrier inhomogeneity, characterized by local low-barrier patches of about 0.5-1.5 μm in diameter. Clearly, the evolution of these low-barrier patches will affect the properties of the fabricated diodes. Indeed, the existence of low-barrier patches contributing to an overall lowering of the average barrier is a common way of modeling non-ideal macroscale diode behavior [24].


Nanoscale characterization of electrical transport at metal/3C-SiC interfaces.

Eriksson J, Roccaforte F, Reshanov S, Leone S, Giannazzo F, Lonigro R, Fiorenza P, Raineri V - Nanoscale Res Lett (2011)

Morphology of the SiC surface and current map of an adjacent Pt contact. AFM morphology of the 3C-SiC(001) surface (a) and C-AFM current map determined at a tip bias of −5 V on an adjacent Pt contact after annealing at 500°C (b).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211166&req=5

Figure 3: Morphology of the SiC surface and current map of an adjacent Pt contact. AFM morphology of the 3C-SiC(001) surface (a) and C-AFM current map determined at a tip bias of −5 V on an adjacent Pt contact after annealing at 500°C (b).
Mentions: While XRD coupled with TEM analysis (see Figure 2) showed that all the Pt have been converted into the stable Pt2Si phase already at 500°C, higher temperature annealing gives rise to increased localized high leakage current areas at the contact interface. Figure 3a shows the morphology of the SiC surface where the large vertical lines are due to several stacking faults bunching together during the growth of the 3C-SiC substrate. Comparing Figure 3a with the current map of an adjacent Pt contact (Figure 3b) determined in the same sample orientation, it is clear that the localized leakage spots occur preferentially along the direction of stacking faults. The total area that is covered by these leaky spots was determined from current maps measured after each annealing temperature and increases from 12% at 500°C to 28% and 55% after annealing at 700°C and 900°C, respectively. These leakage spots suggest a Schottky barrier inhomogeneity, characterized by local low-barrier patches of about 0.5-1.5 μm in diameter. Clearly, the evolution of these low-barrier patches will affect the properties of the fabricated diodes. Indeed, the existence of low-barrier patches contributing to an overall lowering of the average barrier is a common way of modeling non-ideal macroscale diode behavior [24].

Bottom Line: In this case, annealing at 500°C resulted in a reduction of the leakage current and an increase of the Schottky barrier height (from 0.77 to 1.12 eV).A structural analysis of the reaction zone carried out by transmission electron microscopy [TEM] and X-ray diffraction showed that the improved electrical properties can be attributed to a consumption of the surface layer of SiC due to silicide (Pt2Si) formation.The degradation of Schottky characteristics at higher temperatures (up to 900°C) could be ascribed to the out-diffusion and aggregation of carbon into clusters, observed by TEM analysis.

View Article: PubMed Central - HTML - PubMed

Affiliation: CNR-IMM, Strada VIII n, 5, Zona Industriale, 95121, Catania, Italy. jens.eriksson@imm.cnr.it.

ABSTRACT
In this work, the transport properties of metal/3C-SiC interfaces were monitored employing a nanoscale characterization approach in combination with conventional electrical measurements. In particular, using conductive atomic force microscopy allowed demonstrating that the stacking fault is the most pervasive, electrically active extended defect at 3C-SiC(111) surfaces, and it can be electrically passivated by an ultraviolet irradiation treatment. For the Au/3C-SiC Schottky interface, a contact area dependence of the Schottky barrier height (ΦB) was found even after this passivation, indicating that there are still some electrically active defects at the interface. Improved electrical properties were observed in the case of the Pt/3C-SiC system. In this case, annealing at 500°C resulted in a reduction of the leakage current and an increase of the Schottky barrier height (from 0.77 to 1.12 eV). A structural analysis of the reaction zone carried out by transmission electron microscopy [TEM] and X-ray diffraction showed that the improved electrical properties can be attributed to a consumption of the surface layer of SiC due to silicide (Pt2Si) formation. The degradation of Schottky characteristics at higher temperatures (up to 900°C) could be ascribed to the out-diffusion and aggregation of carbon into clusters, observed by TEM analysis.

No MeSH data available.


Related in: MedlinePlus