Solution Q.1.

A particular sample of a semiconductor consists of silicon doped with the group V element, arsenic.
Which of the following properties would apply to this sample?

A. It would have more protons than electrons.
B. It would have more electrons than protons.
C. It would have the same number of electrons and protons.
D. It would have the same number of electrons and holes.


Answer: C

Each atom of silicon and each atom of arsenic would have equal numbers of protons and electrons.
Four of the arsenic's valency electrons would be bonded to silicon atoms while the fifth would enter the conduction band and would be available to carry current.
Current is carried by electrons, but just as in a copper wire, the number of protons is equal to the number of electrons. As one electron goes out another comes in.

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