PV TECHNICAL
The difference between P-type silicon wafer and N-type silicon wafer
Silicon wafers are divided into P-type silicon wafers and N-type silicon wafers. We know that silicon is a 4-valent element with 4 electrons around it. If we combine a pentavalent element such as phosphorus with pure silicon in some form (such as heating), such "silicon" will more easily escape some electrons and exhibit negative electrical characteristics. So it is called N-type silicon (Negative, negatively charged).
Conversely, if a trivalent element such as boron is combined with silicon, there will be more holes, showing positive electrical characteristics. It is called P-type silicon (Positive, positively charged).
When P-type silicon and N-type silicon are combined, a PN junction is formed in the middle region, and the PN junction has unidirectional conductivity.
When light is irradiated on the PN junction, the photovoltaic effect will be generated, and a potential difference will be formed on both sides of the semiconductor.
So making a silicon wafer is actually making a PN junction, which is the process of combining P-type silicon and N-type silicon. There are two methods. The first is to diffuse phosphorus on the basis of P-type silicon to form an n+/p-type structure called P-type silicon wafer. The other is to implant boron on the basis of N-type silicon to form a p+/n-type structure called N-type silicon wafer.
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The manufacturing process of P-type silicon wafer is simple and the cost is low, but the cell efficiency is also low. N-type silicon wafers have a long life, and the cell efficiency can be made higher, but the process is more complicated. But N-type silicon wafers have greater potential, which has reached a consensus. The future development direction must be that N-type silicon wafers gradually replace P-type silicon wafers.
