Influence of Annealing on Crystallinity and Conductivity of p-type Nanocrystalline Si films

Abstract

Nanocrystalline p-type Si:H layers are important for photovoltaic and MOSFET devices. A high conductivity in these layers leads to better voltages in PV devices and to lower series resistance in both PV and MOSFET devices. The lower resistance results in higher channel mobility in MOSFET devices and higher fill factors in PV devices. In this work, we discuss the improvement in conductivity and crystallinity of p-type nanocrystalline Si:H layers by the use of post-deposition annealing. The p layers were deposited at ~ 180°C from mixtures of silane, hydrogen, helium and diborane using ECR plasma deposition techniques. It was found that addition of He to H at first improved both the conductivity and crystallinity, but too much He led to an amorphous phase and lower conductivity. The as-grown films were measured for their crystallinity using both Raman spectroscopy and x-ray diffraction. The conductivity and activation energies were also measured. The films were then successively annealed at temperatures of 250, 300, 350 and 400°C. The crystallinity and grain size were found to increase as the annealing temperature increased. The greatest relative increase was during the initial annealing stages. The conductivity of the films increased significantly as a consequence of the annealing. Conductivities as large as 20 S/cm were obtained in very thin films (~50150 nm). The corresponding activation energies were in the range of 0.03 eV. When these annealed layers were used for MOSFET and PV devices, there was an appreciable increase in performance characteristics.

References

  1. 1

    V. Lumelsky, M. S. Shur, and S. Wagner, IEEE Sensors J. 1, 41 (2001).

    CAS  Article  Google Scholar 

  2. 2

    S. M. Gates, Mater. Res. Soc. Symp. Proc. 467, 843 (1997).

    CAS  Article  Google Scholar 

  3. 3

    I-C. Cheng and S. Wagner: IEE Proc.- Circuits Devices Syst., Vol 150, No. 4, 2003.

    Article  Google Scholar 

  4. 4

    A. Sazonov, D. Striakhilev, C-Z Lee, A. Nathan, Proceedings of the IEEE 93, No. 8, (2005).

  5. 5

    W. E. Spear and P. G. LeComber, Philos. Mag. 33, 935 (1976).

    CAS  Article  Google Scholar 

  6. 6

    J. Kanicki, E. Hassan, J. Griffith, T. Takamori, and J. C. Tsang, Mater.Res. Soc. Symp. Proc. 149, 239 (1989).

    CAS  Article  Google Scholar 

  7. 7

    S. S. He, M. J. Williams, D. J. Stephens, and G. Lucovsky, J. Non-Cryst. Solids 164–166, 731 (1993).

    Article  Google Scholar 

  8. 8

    P. Alpium and V. Chu, J. Vac. Sci. Technol. A, Vol. 21, No.4 , 1048 (2003).

    Article  Google Scholar 

  9. 9

    J. P. Conde, P. Alpuim, and V. Chu, Mater. Res. Soc. Symp. Proc. 715, A3.1.1 (2002).

    Article  Google Scholar 

  10. 10

    G. Willeke, in Amorphous and Microcrystalline Semiconductor Devices, edited by J. Kanicki, (Artech House, Norwood, Massachussets, 1992), Vol. II, pp. 55–88.

    Google Scholar 

  11. 11

    Vikram L. Dalal, Matt Welsh, Max Noack and J. H. Zhu, IEE Proc.-Circuits, Devices and Syst. 150, 316(2003)

    Article  Google Scholar 

  12. 12

    E. Bustarret, M.A. Hachinia, and M. Brunnel, Appl. Phys. Lett. 52, 1675 (1988)

    CAS  Article  Google Scholar 

  13. 13

    H. P. Klug and L.E. Alexander, X-Ray Diffraction Procedure (Wiley, New York,1974)

    Google Scholar 

  14. 14

    X. L. Jiang, Y. L. Lee, and H.L. Zhu, J Phys: Condens Matter 6 (1994) pp 713718

    CAS  Google Scholar 

Download references

Author information

Affiliations

Authors

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Panda, D.P., Dalal, V. Influence of Annealing on Crystallinity and Conductivity of p-type Nanocrystalline Si films. MRS Online Proceedings Library 910, 803 (2005). https://doi.org/10.1557/PROC-0910-A08-03

Download citation