Abstract

Indium–tin–oxide (ITO) is a transparent conductive thin film that is widely used as a top conducive layer in photovoltaic solar cells. However, ITO is sensitive to environmental conditions and the electrical conductivity degrades as a consequence of harsh environmental conditions. Furthermore, the thermal expansion coefficient mismatch between the ITO film and the substrate creates stress/strain on the film when the package is subjected to fluctuating temperatures. This could create micro-cracks and consequently damage the film. Therefore, this study was designed to study the effect of the thermal cycling and thermal aging on the ITO thin films to simulate the effect of continuous high temperatures and fluctuating temperatures that may be applied on the thin films during the usage. In this study, two sets of experiments were conducted on a ${\hbox{60}}~\Omega/\square$ sputter-deposited ITO on ${\hbox{127}}~\mu{\hbox{m}}$ heat stabilized Poly Ethylene Terephthalate (PET) substrate. The first set of experiments contained four samples which were thermally aged at ${\hbox{100}}\ ^{\circ}{\hbox{C}}$ for 30 days and the other set of experiments contained another four samples which were thermally cycled for 900 cycles. The thermal profile consisted of a high temperature of ${\hbox{100}}\ ^{\circ}{\hbox{C}}$, a low temperature of ${\hbox{0}}\ ^{\circ}{\hbox{C}}$, dwell time of 10 minutes, and ramp rate of ${\hbox{10}}^{\circ}{\hbox{C}}/{\min}$, as depicted in Fig. 1 . The initial results showed that the ITO thin film is not stable in the thermal aging experiment and the electrical resistivity gradually increased for all samples until the end of the 30 days. The degradation happened during the thermal cycling as well. However, SEM images show that the morphology of the ITO surface is stable under both conditions. Energy-dispersive X-ray (EDX) spectroscopy analysis showed stability in the ITO thin film in terms of composition. XRD spectra confirmed the improved crystallinity for the thermally aged films, which corresponded to the increased transmission in the visible region.

© 2012 IEEE

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  2. S. H. Mohamed, F. M. El-Hossary, G. A. Gamal, M. M. Kahlid, "Properties of Indium Tin Oxide thin films deposited on polymer substrates," Acta Phys. Polonica A 115, (2009).
  3. Z. Jianming, Indium tin oxide (ITO) deposition, pattering and Schottky contact fabrication Masters thesis Rochester Inst. Technol.RochesterNY (2005).
  4. C.-H. Yang, S.-C. Lee, T.-C. Lin, S.-C. Chen, "Electrical and optical properties of indium tin oxide films," Appl. Phys. Lett. 31, 773-775 (1977).
  5. T. Hanada, T. Negishi, I. Shiroishi, T. Shiro, Thin Solid Films 518, 3089-3092 (2010).
  6. D. R. Cairns, G. P. Crawford, "Electromechanical properties of transparent conducting substrates for flexible electronic displays," Proc. IEEE 93, 1451-1458 (2005).
  7. G. P. Crawford, Flexible Flat Panel Displays (Wiley, 2005).
  8. Y.-S. Chou, J. W. Stevenson, J. Hardy, P. Singh, "Material degradation during isothermal ageing and thermal cycling of hybrid mica seals under solid oxide fuel cell exposure conditions," J. Power Sources 157, 260-270 (2006).
  9. M. J. Rizvi, C. Bailey, H. Lu, "Failure mechanisms of AFC joints under isothermal ageing," Microelectron. J. 39, 1101-1107 (2008).
  10. P. J. Sebastain, "Aging studies on CdSe thin films under ambient conditions," J. Phys. Chem. Solids 52, 963-968 (1998).
  11. A. J. Tosser, C. R. Tellier, J. Launey, "2.25 thickness dependent effects of thermal ageing in thin conductive films," Vacuum 27, 335-338 (1977).
  12. B. Kaouache, P. Gergaud, O. Thomas, O. Bostrom, M. Legros, "Impact of thermal cycling on the evolution of grain, precipitate and dislocation structure in Al, 0.5% Cu, 1% Si thin films," Microelectron. Eng. 70, 447-454 (2003).
  13. T. K. Schmidt, T. J. Balk, G. Dehm, E. Arzt, "Influence of tantalum and silver interlayers on thermal stress evolution in copper thin films on silicon substrates," Scripta Mater. 50, 733-737 (2004).
  14. M. Boehmea, C. Charton, "Properties of ITO on PET film in dependence on the coating conditions and thermal processing," Surface & Coatings Technol. 200, 932-935 (2005).
  15. S. Honda, M. Watamori, K. Oura, "The effects of oxygen content on electrical and optical properties of indium tin oxide films fabricated by reactive sputtering," Thin Solid Films 49, 600-610 (2005).

2010

T. Hanada, T. Negishi, I. Shiroishi, T. Shiro, Thin Solid Films 518, 3089-3092 (2010).

2009

S. H. Mohamed, F. M. El-Hossary, G. A. Gamal, M. M. Kahlid, "Properties of Indium Tin Oxide thin films deposited on polymer substrates," Acta Phys. Polonica A 115, (2009).

2008

M. J. Rizvi, C. Bailey, H. Lu, "Failure mechanisms of AFC joints under isothermal ageing," Microelectron. J. 39, 1101-1107 (2008).

2006

Y.-S. Chou, J. W. Stevenson, J. Hardy, P. Singh, "Material degradation during isothermal ageing and thermal cycling of hybrid mica seals under solid oxide fuel cell exposure conditions," J. Power Sources 157, 260-270 (2006).

2005

D. R. Cairns, G. P. Crawford, "Electromechanical properties of transparent conducting substrates for flexible electronic displays," Proc. IEEE 93, 1451-1458 (2005).

M. Boehmea, C. Charton, "Properties of ITO on PET film in dependence on the coating conditions and thermal processing," Surface & Coatings Technol. 200, 932-935 (2005).

S. Honda, M. Watamori, K. Oura, "The effects of oxygen content on electrical and optical properties of indium tin oxide films fabricated by reactive sputtering," Thin Solid Films 49, 600-610 (2005).

2004

T. K. Schmidt, T. J. Balk, G. Dehm, E. Arzt, "Influence of tantalum and silver interlayers on thermal stress evolution in copper thin films on silicon substrates," Scripta Mater. 50, 733-737 (2004).

2003

B. Kaouache, P. Gergaud, O. Thomas, O. Bostrom, M. Legros, "Impact of thermal cycling on the evolution of grain, precipitate and dislocation structure in Al, 0.5% Cu, 1% Si thin films," Microelectron. Eng. 70, 447-454 (2003).

1998

P. J. Sebastain, "Aging studies on CdSe thin films under ambient conditions," J. Phys. Chem. Solids 52, 963-968 (1998).

1983

K. L. Chopra, S. Major, D. K. Pandya, "Transparent conductors—A status review," Thin Solid Films 102, 1-46 (1983).

1977

A. J. Tosser, C. R. Tellier, J. Launey, "2.25 thickness dependent effects of thermal ageing in thin conductive films," Vacuum 27, 335-338 (1977).

C.-H. Yang, S.-C. Lee, T.-C. Lin, S.-C. Chen, "Electrical and optical properties of indium tin oxide films," Appl. Phys. Lett. 31, 773-775 (1977).

Acta Phys. Polonica A

S. H. Mohamed, F. M. El-Hossary, G. A. Gamal, M. M. Kahlid, "Properties of Indium Tin Oxide thin films deposited on polymer substrates," Acta Phys. Polonica A 115, (2009).

Appl. Phys. Lett.

C.-H. Yang, S.-C. Lee, T.-C. Lin, S.-C. Chen, "Electrical and optical properties of indium tin oxide films," Appl. Phys. Lett. 31, 773-775 (1977).

J. Phys. Chem. Solids

P. J. Sebastain, "Aging studies on CdSe thin films under ambient conditions," J. Phys. Chem. Solids 52, 963-968 (1998).

J. Power Sources

Y.-S. Chou, J. W. Stevenson, J. Hardy, P. Singh, "Material degradation during isothermal ageing and thermal cycling of hybrid mica seals under solid oxide fuel cell exposure conditions," J. Power Sources 157, 260-270 (2006).

Microelectron. Eng.

B. Kaouache, P. Gergaud, O. Thomas, O. Bostrom, M. Legros, "Impact of thermal cycling on the evolution of grain, precipitate and dislocation structure in Al, 0.5% Cu, 1% Si thin films," Microelectron. Eng. 70, 447-454 (2003).

Microelectron. J.

M. J. Rizvi, C. Bailey, H. Lu, "Failure mechanisms of AFC joints under isothermal ageing," Microelectron. J. 39, 1101-1107 (2008).

Proc. IEEE

D. R. Cairns, G. P. Crawford, "Electromechanical properties of transparent conducting substrates for flexible electronic displays," Proc. IEEE 93, 1451-1458 (2005).

Scripta Mater.

T. K. Schmidt, T. J. Balk, G. Dehm, E. Arzt, "Influence of tantalum and silver interlayers on thermal stress evolution in copper thin films on silicon substrates," Scripta Mater. 50, 733-737 (2004).

Surface & Coatings Technol.

M. Boehmea, C. Charton, "Properties of ITO on PET film in dependence on the coating conditions and thermal processing," Surface & Coatings Technol. 200, 932-935 (2005).

Thin Solid Films

S. Honda, M. Watamori, K. Oura, "The effects of oxygen content on electrical and optical properties of indium tin oxide films fabricated by reactive sputtering," Thin Solid Films 49, 600-610 (2005).

K. L. Chopra, S. Major, D. K. Pandya, "Transparent conductors—A status review," Thin Solid Films 102, 1-46 (1983).

T. Hanada, T. Negishi, I. Shiroishi, T. Shiro, Thin Solid Films 518, 3089-3092 (2010).

Vacuum

A. J. Tosser, C. R. Tellier, J. Launey, "2.25 thickness dependent effects of thermal ageing in thin conductive films," Vacuum 27, 335-338 (1977).

Other

Z. Jianming, Indium tin oxide (ITO) deposition, pattering and Schottky contact fabrication Masters thesis Rochester Inst. Technol.RochesterNY (2005).

G. P. Crawford, Flexible Flat Panel Displays (Wiley, 2005).

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