Doctoral research project

Person in charge of the project:
MERTENS ROBERT PIERRE, member of research team Associated Section of ESAT - INSYS, Integrated Systems
Advanced Rear-Side Contact Schemes on i-PERC (Industrial Passivated Emitter and Rear Cell) Solar Cells
Project summary:
In this thesis, a concrete type of solar cells using silicon as material, called i-PERC, is investigated. This type of cell features at the rear side a stack of dielectrics as a passivation layer which is pre-openedin order to allow the subsequent metallization step. While in industry,the cells normally fabricated have a full contacted area on their rear side, the i-PERC has these contacts only locally and distributed over the cell area.The aim of this work is to understand the formation of ahighly doped region around the locally contacted back side, and its benefits over the one created for the full contacted area.For the firsttime for this technology, the in-situ formation of the local contacts has been analyzed and recorded by a heating stage, aiming to mimic the high temperature process that is used to melt the Al layer applied on the cells.It has been seen that Si dissolution in Al plays an important role in the formation of the contacts, as it affects key parameters of the cells. Changes in contact pitch, firing temperature and profile, Al thickness and composition are studied for these i-PERC cells.At the end, the rear reflectance loss mechanisms are also investigated by altering the dielectric layers used for passivation, together with the study of the effect of Si incorporation during the firing step, showing that this Si presence at the back side is the main responsible for the loss observed.
ph.D student :
Faculty of Engineering Science
Doctoral Programme in Engineering (Leuven)

ph.D defence : 10.09.2013
Full text ph.D