optical and structural properties of rf-sputtered si x c 1-x thin films
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PSCM. Optical and structural properties of RF-sputtered Si x C 1-x thin films. International Conference on Nano-Materials and Renewable Energies. Presented by : Abdelilah El Khalfi. EL KHALFI ,E. ECH-CHAMIKH ,Y. IJDIYAOU, M. AZIZAN,A. ESSAFTI - PowerPoint PPT PresentationTRANSCRIPT
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Optical and structural Optical and structural properties of RF-sputtered Siproperties of RF-sputtered SixxCC1-1-
xx thin films thin films
International Conference on Nano-International Conference on Nano-Materials and Renewable EnergiesMaterials and Renewable Energies
Presented by :Abdelilah El Khalfi
PSCM
A.A. EL KHALFI ,E. ECH-CHAMIKH ,Y. IJDIYAOU, M. AZIZAN,A. ESSAFTIEL KHALFI ,E. ECH-CHAMIKH ,Y. IJDIYAOU, M. AZIZAN,A. ESSAFTILaboratoire de Physique du Solide et des Couches Minces, Faculté des Sciences Laboratoire de Physique du Solide et des Couches Minces, Faculté des Sciences Semlalia,Semlalia,Université Cadi ayyad, BP : 2390, Marrakech 4000, MarocUniversité Cadi ayyad, BP : 2390, Marrakech 4000, Maroc
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OUTLINEOUTLINE
• Introduction • Experimental details
- Deposition technique- Characterization techniques
• Results and discussion – Structural properties– Optical properties
• Conclusion & prospects
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IntroductionIntroduction
• Many works, on amorphous silicon carbide (a-SixC1-x), realized by RF-Sputtering by :
- Multilayers method (silicon and graphite targets) - From silicon carbide target
- From composite target (co-sputtering)
• In this work : co-sputtering (with RF power varying from 150 to 350W and Si/C surface rate coverage from 17% to 33% of total graphite target surface)
• a-SiC is mach attractive in the nano-materials field.
Some applications : Electronic devices; Anti-wear, protective and
hard surface coatings; solar cells
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Experimental detailsExperimental details
Experimental conditions:
Residual pressure : 10-6 mbarArgon pressure : 10-2 mbarComposite target : Graphite target
(5N) with silicon chips (fragments ) (17% to 33% of total graphite target surface)
RF power : 150 W, 250 W and 350 W.
Deposition time : 2 hours for all samples prepared
- Deposition technique : RF-sputtering
silicon chips
Graphite target
Composite target
(Silicon chips + graphite target )
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- Characterization- Characterization techniquestechniques
Structural properties of thin films
Optical properties : Absorption coefficient Refractive index Optical band gapThin films thickness
Grazing incidence X-Ray Diffraction (GIXD)
UV-Visible-NIR Spectroscopy
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Results and discussion Results and discussion - GIXD Measurements- GIXD Measurements
• Typical GIXD diagrams of as deposited a-SixC1-x thin films : Amorphous films
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Optical measurements - Theoretical formula
Transmission Coefficient :
Refractive index :
Films thickness :
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Absorption Coefficient :
For amorphous thin films : the optical band gap is indirect
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- Optical - Optical transmission transmission
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Variation of the deposition rate versus Variation of the deposition rate versus the surface coverage Si/C and the RF the surface coverage Si/C and the RF
powerpower
For the explored ranges of Si compositions and RF powers, the deposition rate, of the a-SixC1-x thin films, increases with the RF power and the Si fragments surface coverage ratio.
- Films thickness- Films thickness
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- Optical band gap- Optical band gap
Variation of the optical band gap versus the Variation of the optical band gap versus the surface coverage Si/C and the RF powersurface coverage Si/C and the RF power
The optical band gap increases from 1,7 to 2,2 eV with The optical band gap increases from 1,7 to 2,2 eV with increasing the Si content or decreasing the RF powerincreasing the Si content or decreasing the RF power.
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- Refractive - Refractive indexindex
Variation of the refractive Variation of the refractive indexindexWith the low of With the low of Cauchy Cauchy ; ; n(n() = n(IR) + b/() = n(IR) + b/(²)²)
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Refractive index (in IR)Refractive index (in IR)
•The refractive index n(IR) varies from 2 to 2,5
Variation of the refractive index (IR) versus Variation of the refractive index (IR) versus the surface coverage Si/C and the RF power : the surface coverage Si/C and the RF power : is the same of thickness film is the same of thickness film
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Conclusion Conclusion
• All the as deposited SixC1-x thin films are amorphous.
• The deposition rate of the a-SixC1-x thin films increases with the RF power and the Si fragments surface coverage ratio.
• The optical band gap increases from 1,7 to 2,2 eV with increasing the Si content or decreasing the RF power.
• The refractive index n(IR) varies from 2 to 2,5
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ProspectsProspects
• Complete the results obtained by other analytical techniques such as RBS or XPS, RAMAN, IR, electrical measure
• Enlarge the target surface covered (by the Si ships) : from 0% to 100%
• Study the surface roughness and electronic density by Grazing incidence X-Ray Reflectometry (GIXR)
• Annealing effect on the properties of SixC1-x• Addition of gases (H2, O2 and N2) to produce SixC1-
x:H,O,N thin films
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Thank you for Thank you for your attention your attention