Question

In the energy band diagram of a material shown below, the open circles and filled circles denote holes and electrons respectively. The material is a/an

• A. p-type semiconductor
• B. insulator
• C. metal
• D. n-type semiconductor

Answer 1

Answer: (A)

p-type semiconductor

Answer 2

The given figure represents $p$-type semiconductor as described below : When one of the silicon atoms (valence =4) has been replaced by an atom of aluminium (valence $=3$ ), the aluminium atom can bond covalently with only three silicon atoms, so there is now a "missing" electron (a hole) in one aluminium-silicon bond with a small expenditure of energy, an electron can be torn from a neighbouring silicon-silicon bond to fill this hole, thereby creating a hole in that bond. Similarly, an electron from some other bond can be moved to fill the second hole. In this way, the hole can migrate through the lattice.