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With Which one of the following elements silicon should be doped so as to give p-type of semiconductor?A. GermaniumB. ArsenicC. SeleniumD. Boron |
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Answer» Correct Answer - 4 To get `p`-type of semiconductor, we should dope `Si` with electron deficient species such as boron that has fewer than four valance electron. Boron atoms replaces some silicon atoms. After a boron atom forms bonds to four silicon atoms, one of the boron silicon bonds has only one electron in it. We can think of this situation as a vacancy , or positively charge "hole" in the bonding orbital. An electron from a neighbouring atom can move to occupy this hole Now a hole exists on the neighbouring atom and an electron from another atom can move into it. and so forth.the result is the movement of positively charged holes in the semiconductor . Boron -doped sillicon is an example of a p-type semiconductor because the charge is carried by positive holes. Doping with electron rich impurities such as arsenic and selenium will result in an n-type semiconductor. |
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