Factorial Experiment Study on Deposition Parameter Dependence of the Energy Bandgap of a-SiGe: H Thin Film Prepared by Plasma Enhanced Chemical Vapor Deposition

Abstract:

The energy bandgap (E_g) of a-SiGe:H thin film prepared by plasma enhanced chemical vapor deposition (PECVD) is greatly dependent on the deposition conditions. By controlling the flow rates of the supplied gas sources, the total gas pressure, the plasma power, the substrate temperature and so on, E_g can be adjusted. Although the influence of the above deposition factors has been investigated individually, which factor is the most important is still not clear. Here, a 6-factor 5-level factorial experiment was designed to investigate the influence of the deposition factors comprehensively. By making the main effect analysis to E_g, not only the influence of each deposition factor was deduced, but also the most critical factors were selected out. It was found that the flow rates of SiH₄ and GeH₄, and the total gas pressure played the important roles for the E_g adjustment of a-SiGe:H thin film. So much attention can be only paid to optimize such critical factors with other factors as some default values according to the experience. Thus, the work load can be reduced greatly.

• Periodical: Advanced Materials Research (Volumes 457-458)
• Pages: 663-667
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.457-458.663
• Online since: January 2012
• Authors: Lei Zhao, Bao Jun Yan, Ben Ding Zhao, Hong Wei Diao, Wen Jing Wang
• Keywords: a-SiGe:H, Energy Band Gap, Factorial Experiment, PECVD

References

[1] A. Terakawa, M. Shima, K. Sayama, H. Tarui, H. Nishiwaki, S. Tsuda, Optimization of a-SiGe: H alloy composition for stable solar cells, Jpn. J. Appl. Phys. 34 (1995) 1741-1747.

DOI: 10.1143/jjap.34.1741

[2] A.H. Mahan, P. Raboisson, R. Tsu, Influence of microstructure on the photoconductivity of glow discharge deposited amorphous SiC: H and amorphous SiGe: H alloys, Appl. Phys. Lett. 50 (1987) 335-337.

DOI: 10.1063/1.98192

[3] B.E. Pieters, M. Zeman, R.A.C.M.M. van Swaaij, W.J. Metselaar, Optimization of a-SiGe: H solar cells with graded intrinsic layers using integrated optical and electrical modeling, Thin Solid Films 451-452 (2004) 294-297.

DOI: 10.1016/j.tsf.2003.11.029

[4] D. Lundszien, F. Finger, H. Wagner, A-Si: H buffer in a-SiGe: H solar cells, Sol. Energy Mater. Sol. Cells Vol. 74 (2002) 365-372.

DOI: 10.1016/s0927-0248(02)00096-x

[5] B. Yan, G. Yue, L. Sivec, J. Yang, S. Guha, C. Jiang, Innovative dual function nc-SiOx: H layer leading to a >16% efficient multi-junction thin-film silicon solar cell, Appl. Phys. Lett. 99 (2011) 113512.

DOI: 10.1063/1.3638068

[6] J. Yang, A. Banerjee, S. Guha, Triple-junction amorphous silicon alloy solar cell with 14. 6% initial and 13. 0% stable conversion efficiencies, Appl. Phys. Lett. 70 (1997) 2975-2977.

DOI: 10.1063/1.118761

[7] M. Zeman, I. Ferreira, M.J. Geerts, J.W. Metselaar, The influence of deposition parameters on the growth of a-SiGe: H alloys in a plasma CVD system, Appl. Surf. Sci. 46 (1990) 245-248.

DOI: 10.1016/0169-4332(90)90151-o

[8] A. Rashad, J.V. Sali, B.R. Marathe, M.G. Takwale, D. Shaligram, The effect of substrate temperature on P-CVD deposited a-SiGe: H films, Sol. Energy Mater. Sol. Cells 57 (1999) 209-216.

DOI: 10.1016/s0927-0248(98)00147-0

[9] S. Hazra, A.R. Middya, S. Ray, C. Malten, F. Finger, Role of deposition parameters on the photovoltaic quality of amorphous silicon germanium alloys: correlation of microstructure with defect density and electronic transport, J. Phys. D: Appl. Phys. 34 (2001).

DOI: 10.1088/0022-3727/34/16/312

[10] J. Tauc, Optical properties and electronic structure of amorphous Ge and Si, Mater. Res. Bull. 3 (1968) 37-46.