1. M.S. Hossain, N.A. Khan, M. Akhtaruzzaman, A. R. M. Alamoud and N. Amin Solar Energy Research Institute (SERI) Universiti Kebangsaan Malaysia (UKM) Selangor, Malaysia

2.  Introduction:  Solar Cell Classifications  Prospects of Zn x Cd 1-x S for CdTe Solar Cells  Structure of Zn x Cd 1-x S/CdTe Solar Cells  Objective  Methodology  Advantages of RF Magnetron Sputtering  Result and Discussions  Conclusion

3. PV Cells Thin Film Poly-Crystalline Silicon Compound Crystalline Amorphous Others Mono-Crystalline Poly-Crystalline GaAs CdTe,CIGS, CZTS (Organic-Materials, Dye etc.) PV Cell Electricity Heat Sunlight

4. Prospects of Zn x Cd 1-x S for CdTe Solar Cells:  CdTe is considered as one of the leading materials for cost-effective photovoltaic (PV).  The bandgap of CdTe is around (1.5 eV), close to the ideal value for photovoltaic conversion efficiency. It has high optical absorption coefficient and high chemical stability.  The formation of a stable, low resistance, non-rectifying contact to p- CdTe thin-film is one of the major and critical challenges for efficient and stable CdTe solar cells.  Zn x Cd 1-x S window layer is preferable instead of CdS for CdTe solar cells in considering bandgap and prevention of excessive pinholes for film less than 100 nm.

6.  Growth optimization of Zn x Cd 1-x S film for CdTe solar cell through structural and morphological study.  Effect of thickness variation on structural, morphological properties of CdTe thin films.  Impact of ITO and FTO on the performance of Zn x Cd 1-x S/CdTe solar through RF magnetron sputtering

7.  Glasses were cleaned in an ultra-sonic bath.  Cleaned glasses were dried by dry N 2.  Complete Zn x Cd 1-x S/CdTe solar cells were deposited layer by layer onto ultrasonically cleaned glass substrates by RF sputtering technique.  After deposition, Zn x Cd 1-x S and CdTe were characterized through EDX, XRD and SEM analysis.  Complete cells were tested through I-V tester

8. Process Parameters of CdTe, BSF and Ag metal used in sputtering system Sample No. RF P OWER (W) Operating Pressure (mTorr) Argon Flow (sccm) Substrate Temp. ( 0 C) CdTe Thickness ( μ m) 13516 2604.5 23516 2603.5 33516 2602.8 43516 2601.5 53516 2601.1 63516 2600.58 Process parameters ZnTeCuTe Ag metal Deposition Temp.250 0 C Base pressure 2×10 -5 T Working pressure18 mT Argon gas flow18 sccm17 sccm 16 sccm RF power50 W 40 W50 W Approx. thickness100 nm40 nm60 nm100 nm

9.  The sputtering technique is well suited for industrial large scale production and it has been applied successfully to CdTe solar cell fabrication.  The deposited film thickness can be monitored and controlled to achieve any thickness from nm to μm.  All the layers of the designed cells with desired thickness can be deposited in one chamber by sputtering, without breaking the vacuum RF magnetron Sputtering machine used in this work

10.  EDX and XRD Analysis of ZnxCd1-xS Thin Film Figure: EDX and XRD spectra of Zn x Cd 1-x S thin film

11. Figure : Surface and cross-section images of Zn x Cd 1-x S thin films.  SEM Analysis of ZnxCd1-xS Thin Film

12.  The (111) orientation is the close packing direction of zinc-blende structure and this type of orientation is often observed in poly crystalline films.  XRD Analysis of CdTe Thin Film

13. Figure : Surface and cross-section images of CdTe thin film for variable thickness (1.1 μm and 4.5 μm)

14.  Cells fabricated in ITO coated glasses show a bit higher performance than cells fabricated in FTO coated glasses Figure : J-V characteristics of Zn x Cd 1-x S/CdTe solar cell in which back contact deposited by sputtering and BSF used as ZnTe for optimization of ITO and FTO with CdTe 4.5 μ m and 1.1 μ m

15. Figure : J-V characteristics of Zn x Cd 1-x S/CdTe solar cell in which back contact deposited by sputtering and BSF used as Cu 2 Te for optimization of ITO and FTO with CdTe 4.5 μ m and 1.1 μ m  Cells fabricated with ZnTe BSF show a bit higher performance than cells fabricated with Cu 2 Te in comparing the result in the previous slide.

16.  The structural and morphological study of window and absorber layers of Zn x Cd 1-x S/CdTe solar cells have been investigated by XRD, EDX and SEM analysis.  The complete Zn x Cd 1-x S/CdTe solar cells fabricated in ITO and FTO coated glasses with different BSF (ZnTe, Cu 2 Te) have been examined.  Cells fabricated in ITO coated glasses using ZnTe BSF result better performance in comparison to FTO coated glass cells using Cu 2 Te BSF.

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