Pure silicon can be changed into p –type semiconductor by adding an impurity. Explain how this is achieved.

K.C.S.E Physics Q & A - MODEL 2003PP1QN19

Pure silicon can be changed into p –type semiconductor by adding an impurity. Explain how this is achieved.

answer

• Dope with group III element (e.g. Boron, Al, Ga). Three silicon electrons pair up with impurity atom electrons. One electron of silicon has no electron to pair up; hence a hole is created(For correct structure without explanation but showing a group three element.