In-situ PL and MPL measurements during for solar cell optimization

Plasma-enhanced chemical vapour deposition of silicon thin films, in particular hydrogenated amorphous silicon (a-Si:H) is currently used to provide excellent surface passivation to c-Si solar cells. However, the optimization of the process conditions (RF power, substrate temperature, gaz mixture and total pressure) is often done by depositing samples and characterizing them after deposition, which is a time consuming process and makes it difficult to identify the key factors leading to surface passivation (chemical and field effect passivation) as well as to defect creation via ion bombardment, UV-light exposure from the plasma, excessive hydrogen accumulation at the interface (blistering) and their combined effects with the process temperature.

The objective of this internship will be to use an in situ PL and MPL setup optimized in the framework of the PhD thesis of Mateusz Poplawski, to gain further understanding of the above processes and underlying mechanisms. The figure below gives an example of the effects of annealing and hydrogen plasma treatment on a c-Si wafer symmetrically passivated by a stack of an a-SiOx:H/intrinsic a-Si:H/p-type a-Si:H.

Contacts: Prof. Pere Roca i Cabarrocas – pere.roca@polytechnique.edu

Mateusz Poplawski – mateusz.Poplawski@ipvf.fr