The properties of floating-zone silicon seem greater than Czochralski silicon. If we produce these two materials through standard solar cells' production lines, what are the differences in the solar cells produced?
Both are single crystal but FZ is more pure. The metallic contaminants are reduced slightly, but most important for p-type Si is the reduction of the oxygen content. Boron-oxygen complexes are a major limitation for solar cells from p-type Cz but play a much smaller role in FZ because there is less oxygen.
Hi, Schnabel, it's a good answer. Do you think the solar cells' product process, such as aluminum paste and sintering procedure, may decrease the properties of FZ silicon, since it is already a high quality crystal?
Well it doesn't affect the crystal quality but the pastes are dirtier than both Cz and FZ silicon. However, the sintering is very rapid so to my knowledge there is no contamination of the bulk crystal, just a non-ideal contact region at/near the surface. However, there's other experts on this, maybe repost it as a separate question.
The purer material results in much longer recombination and generation lifetimes so the diodes are much better quality in both forward and reverse biasoperating modes.
Hi, Hall. I agree with you. I just wonder that the purer materials are, the easier to be contaminated.
Depending on your thermal budget, you might also induce stresses that degrade the carrier life-time of your FZ so its performance might decay and degrade it closer to Cz silicon.
Personally, the quality of a cell could be regarded as a value (very sensititive to Voc) J0,total, equals J0,front + J0,bulk + J0,rear. In the same cell fabrication process, CZ and FZ wafer shold have the same J0, front and J0,rear in an ideal assumption. The only difference is the bulk lifetime.
According to my experience, the metallizaiton process of cell can not induce metal contamination to the bulk if the process controlled properly.
- Badges
- Science topic