1. Optical and structural properties of RF- sputtered Si x C 1-x thin films International Conference on Nano-Materials and Renewable Energies International Conference on Nano-Materials and Renewable Energies Presented by : Abdelilah El Khalfi PSCM 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

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

3. Introduction 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

4. Experimental details Experimental conditions: Residual pressure : 10 -6 mbar Argon pressure : 10 -2 mbar Composite 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 )

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

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

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

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

9. - Optical transmission

10. 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-SixC1-x thin films, increases with the RF power and the Si fragments surface coverage ratio. - Films thickness

11. - 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 eV with increasing the Si content or decreasing the RF power The optical band gap increases from 1,7 to 2,2 eV with increasing the Si content or decreasing the RF power.

12. - Refractive index Variation of the refractive index With the low of Cauchy ; n(  ) = n(IR) + b/( ²) n(  ) = n(IR) + b/( ²)

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

14. 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

15. 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 SixC1-x Addition of gases (H2, O2 and N2) to produce SixC1-x:H,O,N thin films

16. Thank you for your attention