Programm Photovoltaik Ausgabe 2008 ... - Bundesamt für Energie BFE

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Fig. 7: View of the new fully automated cluster system at IMT. One chamber is operational whereas
the second plasma box is being installed at the time of writing this report.
Collaboration and synergies with other projects/institutes
IMT continues to be involved into the European projects ATHLET and FLEXCELLENCE. A strong
synergy is realized between all these projects and this running SFOE project, with indirect benefits for
companies such as OC Oerlikon and VHF-Technologies. A project (1.3.2006-28.2.2008) with the Danish
company “Photosolar” financed by Energienet.dk continues to allow synergy for nip devices development.
Regular academic contacts/scientific and sample exchanges have been maintained throughout 2007
both with national (CRPP-EPFL, EMPA, HE-Arc,..) and international (University of Ljubljana, University
of Patras, IPV Juelich, Academy of Science of Prague, ECN….). IMT was one of the instigators of the
Swiss thin Film PV project, coordinated now by EMPA (Sponsored by CCEM-CH and Swiss Eletric
Research). One Phd. student performed measurements at HMI in Berlin. One IMT Phd. student stayed
for six months at NREL (Golden, CO, US) and developed new technique for thin film Si analyses. In
2007, IMT organized two “Thin film PV schools” for industries. These schools last 5-9 days and offer
an in-depth introduction to the science and technology of thin film silicon.
Evaluation for 2007 / perspectives for 2008
2007 has been a fruitful year as it has allowed both the introduction of new concepts in the thin film
silicon devices (e.g. SiOX intermediate reflector) and a much better understanding of the critical interaction
between the substrate morphology and the PECVD thin film growth. This knowledge is now
useful for virtually all thin film silicion devices, prepared both on glass and plastic. In general, we have
now much better tools (receipts, processes, TCO’s, backreflector) in hands to fabricate high efficiency
devices on a variety of different TCO's or substrates, and this with different device concepts. In particular,
micromorph solar cells with initial efficiency above 12% can be routinely prepared and this can
be achieved either with devices with a high Voc and FF or with a high current. The reasons for the
difficulty to achieve simultaneously both high VOC FF and current are now better understood and give
clear guidelines for the next steps.
In the next years, the laboratory will continue the upgrade of its infrastructure with the introduction of
new state-of-the-art multi chamber cluster systems (small area systems, with up to 7 chambers) allowing
the introduction of more innovative layers and processes. In parallel, it will continue its work with
the development of high efficiency devices and development of processes which will be relevant for
the next generation production lines based on thin film silicon.
Thin film silicon solar cells: advanced processing and characterization, C. Ballif, IMT
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