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Thursday 13th june 2019, 10:00, at ICD of UTT

Shijian WANG defends his PhD thesis

« Metallic nanostructure W-shaped for Nano-optic and Numerical simulation of tandem solar cells on silicon »

surface plasmons ; nano-structuration on silicon ; nano-optics ; numerical simulation ; tandem solar cells


The works presented in this PhD Thesis consists of two main subjects.

The first part deals with an original plasmonic structure based on a new approach of nanostructuration. The geometry is described as a gold layer folded into a “W” shape. We named it as Origami because of the Japanese words: ‘ori’, fold; ‘gami’, paper. Thanks to an original technology using a Silicium matrix, structures are fabricated for a 50-nm thickness gold layer with a periodicity of 400 to 1000 nm. The complexity and originality of the response comes from the presence of regular ripples with high local field enhancement factors that may couple into a plasmonic chain mode. Meanwhile optical performance measurement and simulation fitting results are in good agreement. All in all, this new structure possesses various promising fields of applications, such as sensor based on LSPR. Corresponding simulation for this type of sensor, simulated by RCWA, shows it possesses an excellent sensitivity in the wavelength range of 760-900 nm.

The second part deals with Numerical simulation of III-V/Si tandem solar cells consisting of an active layer of GaAsPN. This type of solar cell owns high theoretical efficiency and low cost. SILVACO software is applied to do corresponding simulation for the preliminary research. The main work focuses on top cell study due to the mature bottom Si solar cell fabrication. Simulation results assure of the best active layer thickness, and indicate that graded layers can decrease the band offset effect existing between GaAsPN and N-GaP layers, meanwhile we have found that the GaP(n++)/Si(p++) is the relative better tunnel junction in this configuration. Finally, the coarse fitting between simulation and experiment shows the same tendency, but also there is room for improvement.


Committee members
James CONNOLLY Professor, GeePs, IPVFExaminator
Pierre-Michel ADAM Professor, ICD, UTTExaminator
Alain MORAND Ass. Professor, IMEP-LAHC, Université Grenoble-AlpesMember
Yun SUN Ass. Professor, Institute of Microelectronics, Chinese Academy of SciencesMember
Alain ROLLAND Professor, FOTON Institute, University of RennesPh.D. Supervisor
Rémi VINCENT Ass. Professor, ICD, UTTPh.D. Supervisor