Programm Photovoltaik Ausgabe 2009 ... - Bundesamt für Energie BFE

Eidgenössisches Departement für
Umwelt, Verkehr, Energie und Kommunikation UVEK
Bundesamt für Energie BFE
HIGH-EF - LARGE GRAINED, LOW STRESS
MULTI-CRYSTALLINE SILICON THIN FILM
SOLAR CELLS ON GLASS BY A NOVEL
COMBINED DIODE LASER AND SOLID
PHASE CRYSTALLIZATION PROCESS
Annual Report 2008
Author and Co-Authors X. Maeder, J. Michler
Institution / Company Empa – Materials Science and Technology
Address Feuerwerkerstr. 39, CH-3602 Thun, Switzerland
Telephone, E-mail, Homepage +41 (0) 33 228 29 59, Xavier.Maeder@empa.ch, www.empa.ch
Project- / Contract Number EU FP7 Grant Agreement Num. 213303
Duration of the Project (from – to) 01.01.2008 - 31.12.2010
Date 13.01.2009
ABSTRACT
The objective of the High-ef project is to provide the silicon thin film photovoltaic (PV) industry with a
process allowing high solar cell efficiencies (>10%) by large grains in the material at competitive production
cost. The process is based on a combination of laser melt-mediated crystallization of an
amorphous silicon (a-Si) seed layer ( 2�m) of the
seed layer by solid phase epitaxy (SPE) process. The combined laser –SPE process represents a
major break-through in silicon thin film photovoltaic on glass as it substantially enhances the grain
size and reduces the defect density and the stress levels compared to e.g. standard solid phase crystallisation
processes (SPC) on glass which provides grains less than 10�m in diameter with a high
density of internal extended defects. A low cost laser processing will be developed in High-ef using
highly efficient laser diodes with a wide line focus for the crystallisation of a large module area within
one scan. The main tasks of Empa in the project are i) grains size, grain boundaries, texture and lattice
defects characterizations of the Si thin film by electron backscatter diffraction techniques (EBSD),
ii) elastic strains et residual stresses measurements by EBSD and iii) mechanical testing of the material.
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