PSCM International Conference on NanoMaterials and Renewable Energies

PSCM International Conference on Nano-Materials and Renewable Energies Optical and structural properties of RFsputtered Six. C 1 -x thin films Presented by : Abdelilah El Khalfi A. EL KHALFI , E. ECH-CHAMIKH , Y. IJDIYAOU, M. AZIZAN, A. ESSAFTI Laboratoire de Physique du Solide et des Couches Minces, Faculté des Sciences Semlalia, Université Cadi ayyad, BP : 2390, Marrakech 4000, Maroc

OUTLINE • Introduction • Experimental details - Deposition technique - Characterization techniques • Results and discussion – Structural properties – Optical properties • Conclusion & prospects

Introduction • a-Si. C is mach attractive in the nano-materials field. Some applications : Electronic devices; Anti-wear, protective and hard surface coatings; solar cells • Many works, on amorphous silicon carbide (a-Six. C 1 -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 350 W and Si/C surface rate coverage from 17% to 33% of total graphite target surface)

Experimental details - Deposition technique : RF-sputtering Experimental conditions: Residual pressure : 10 -6 mbar Argon pressure : 10 -2 mbar Composite target : Graphite target (5 N) 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 Graphite target silicon chips Composite target (Silicon chips + graphite target )

- Characterization techniques Grazing incidence X-Ray Diffraction (GIXD) UV-Visible-NIR Spectroscopy Structural properties of thin films Optical properties : ü Absorption coefficient ü Refractive index ü Optical band gap Thin films thickness

Results and discussion - GIXD Measurements • Typical GIXD diagrams of as deposited a-Six. C 1 -x thin films : Amorphous films

Optical measurements - Theoretical formula Transmission Coefficient : Refractive index : Films thickness :

Absorption Coefficient : For amorphous thin films : the optical band gap is indirect

- Optical transmission

- Films thickness Variation of the deposition rate versus the surface coverage Si/C and the RF power For the explored ranges of Si compositions and RF powers, the deposition rate, of the a-Six. C 1 -x thin films, increases with the RF power and the Si fragments surface coverage ratio.

- Optical band gap Variation of the optical band gap versus the surface coverage Si/C and the RF power The optical band gap increases from 1, 7 to 2, 2 e. V with increasing the Si content or decreasing the RF power.

- Refractive index Variation of the refractive index With the low of Cauchy ; n(l ) = n(IR) + b/(l²)

Refractive index (in IR) Variation of the refractive index (IR) versus the surface coverage Si/C and the RF power : is the same of thickness film • The refractive index n(IR) varies from 2 to 2, 5

Conclusion • All the as deposited Six. C 1 -x thin films are amorphous. • The deposition rate of the a-Six. C 1 -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 e. V with increasing the Si content or decreasing the RF power. • The refractive index n(IR) varies from 2 to 2, 5

Prospects • 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 Six. C 1 -x • Addition of gases (H 2, O 2 and N 2) to produce Six. C 1 -x: H, O, N thin films

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