We calculate the maximal absorption enhancement obtainable by guided mode excitation in a weakly absorbing dielectric slab over wide wavelength ranges. The slab mimics thin film silicon solar cells in the low absorption regime. We consider simultaneously wavelength-scale periodicity of the texture, small thickness of the film, modal properties of the guided waves and their confinement to the film. Also we investigate the effect of the incident angle on the absorption enhancement. Our calculations provide tighter bounds for the absorption enhancement but still significant improvement is possible. Our explanation of the absorption enhancement can help better exploitation of the guided modes in thin film devices.
© 2012 Optical Society of America
Original Manuscript: August 23, 2012
Revised Manuscript: October 22, 2012
Manuscript Accepted: October 23, 2012
Published: December 4, 2012
Ali Naqavi, Franz-Josef Haug, Corsin Battaglia, Hans Peter Herzig, and Christophe Ballif, "Light trapping in solar cells at the extreme coupling limit," J. Opt. Soc. Am. B 30, 13-20 (2013)