Optimization of the Si bottom subcell for III-V on Si multi-junction solar cells

Electrical Engineering Seminar 

Optimization of the Si bottom subcell for III-V on Si multi-junction solar cells
Diego Martín
Department of Electrical Engineering of the Rey Juan Carlos University (Madrid, Spain)

The integration of III-V semiconductors on Si substrates has received a lot of attention over the last years. As a result of this impulse, good quality metamorphic III-V materials and the first complete devices have been reported, demonstrating great promise towards the achievement of highly efficient III-V/Si solar cells. Most of the efforts have been focused on the optimization of the heteroepitaxial growth of III-V compounds on Si with the primary goal of the minimization of crystal defects. Nonetheless, little work has been done on optimizing the device configuration and its processing. Typically, the few implementations of these devices reported so far have used the processing strategies of III-V solar cells. However, the Si subcell demands a processing more aligned with conventional silicon PV technology to fully exploit its photovoltaic potential. The development of an adapted design for the Si subcell is consequently a must to ensure a high efficient device so that a GaAsP/Si dual-junction solar cell with an efficiency exceeding 30% can be eventually obtained.

In this talk, I will discuss some experimental results from our MOVPE-based process, as the evolution of the Si minority carrier lifetime during the III-V growth, or the Si subcell emitter formation by PH3 diffusion. In addition, the adequacy of different well-known alternatives for the Si rear-surface passivation (Al-BSF, PERC- and HIT-like schemes) will be discussed. A comparison of the Si subcell performance using numerical simulations with Silvaco TCAD for the reviewed alternatives will be presented.

Biography
Diego Martín is an Assistant Professor at the Department of Electrical Engineering of the Rey Juan Carlos University (Madrid, Spain), and a member of the III-V Semiconductors group at the Solar Energy Institute, Technical University of Madrid (Spain). He received his Ph.D. degree from the Technical University of Madrid in 2004, working on GaSb photovoltaic cells for thermophotovoltaic applications. He was at the department of Computer Engineering, CES Felipe II, Universidad Complutense of Madrid from 2005 to 2014. His current research interests include high concentration III-V solar cells and the design and simulation of III-V on Si multi-junction solar cells.

Monday, June 1, 2015
11 a.m.
Becton 408, 15 Prospect Street
Host: Prof. Minjoo Larry Lee