Light absorption by thin-ﬁlm amorphous Si solar cells patterned with metallic nanogratings is investigated theoretically. Propagative bounded modes that include the surface plasmon polariton (SPP) and the photonic mode (PM) are extracted from the total field to quantitatively evaluate their contribution to the light absorption. Our results show that after removing the propagative bounded modes from the total field, the residual field still contributes to a major part of the total light absorption. This proves, at a quantitative level, that the light absorption of the structure is largely attributed to the residual field that is composed of unbounded or evanescent modes arising from the grating scattering, and the SPP and the PM do not play a dominant role, which is out of the previous intuitive expectations.
© 2013 Optical Society of America
Original Manuscript: October 10, 2012
Revised Manuscript: December 28, 2012
Manuscript Accepted: January 11, 2013
Published: February 13, 2013
Pan Chen, Ying Zhong, and Haitao Liu, "Role of surface plasmon polaritons and photonic modes in light absorption by thin-film solar cells patterned with metallic nanogratings," Opt. Lett. 38, 573-575 (2013)