CHEETAH WEBINAR - Dislocations in multicrystalline silicon - Nucleation, growth and relaxation of dislocations in directionally solidified multicrystalline silicon
Webinar - June, 9th 2017 - 11:00 – 12:15 CEST
Dr. Birgit Ryningen
Multicrystalline silicon is the most promising candidate for enabling large scale production of low cost solar cells. The efficiency of such cells is fundamentally limited by the presence of crystal defects, and there is little absolute knowledge about the defect generation mechanisms, because all generation and development happens at too high temperature to be observed by conventional characterization techniques.
Crystal defects generated during the directional solidification process, particularly dislocations and sub grain boundaries, are well proven to be the factor mostly limiting the cell efficiency of multicrystalline silicon. This means that keeping growth conditions optimal becomes extremely important. Unless the density and properties of the crystal defects are under control, any measure in other parts of the value chain, ranging from reduction of contamination, to efforts during cell processing such as gettering will have very limited effect. In contrast, recent development in crystallization process control (development of so-called High Performance Multicrystalline Silicon) has shown the large potential in efficiency improvement by reducing the amount of crystal defects.