Determine whether each statement below about conduction in semiconductors is true or false.
1. after a photon "kicks" an electron into the upper conduction band, the electron moves to the p-type side of the p-n junction.
2. an n-type semiconductor has missing electrons (or holes) in the lower energy valence band.
3. electrons cannot move in a full valence band.

1. True

2. False

3. True

Explanation:

Semiconductors are the materials whose conduction is intermediary to that of the conductor and insulator and can be made more conducting by mixing impurities or we call it as doping.

In semiconductors, the concentration of the holes in the valence band and the electrons in the conduction band is usually very small and can be varied noticeably by doping.

(1) After being excited by a photon, an electron can move to the conduction band as a hole is created in the valence band band and this hole moves to the p-side of the p-n junction.

(2) It is not the n-type but the p-type semiconductor with missing electrons or holes in the valence band of lower energy.

(3) Electrons are free to move in a partially filled conduction band and valence band.

There is no movement of electrons along the band which are completely full or totally vacant.