CSC258H5- Midterm Exam Guide - Comprehensive Notes for the exam ( 16 pages long!)
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N-type - dope the silicon with phosphorous which had 5 electron, so now the material has some extra electrons which can flow through the material. P -type - dope the silicon with boron which as 3 electrons so there are gaps in the material without electrons. Note that both n-type and p-type material are still neutral charge since number of protons still equals number of electrons. Depletion layers if you put an n-type material next to a p-type then the "extra" electrons from the n type are drawn to the holes in the p type . Pn junctions if you apply a positive charge to the p-type and a negative charge to n-type then the depletion layer would decrease due to forward bias ( the electrons in depletion layer attracted to positive charge. The electrons in n-type are repelled by the negative charge and will be attracted to the holes).