Chapter 1 (Semicon) - Floyd

Each atom in a silicon crystal has

• Four valence electrons

• Four conduction electrons

• Eight valence electrons, four of its own and four shared

• No valence electrons because all are shared with other atoms

1.     An atom consists of

• a.    One nucleus and only one electron

• b.    One nucleus and one or more electrons

• c.    Protons, electrons and neutrons

• d.    Answers (b) and (c)

Recombination is when

• An electron falls into a hole

• A positive and a negative ion bond together

• A valence electron becomes a conduction electron

• A crystal is formed

In an intrinsic semiconductor,

• There are no free electrons

• The free electrons are thermally produced

• There are only holes

• There are as many electrons as there are holes

• Answers (b) and (d)

The purpose of a pentavalent impurity is to

• Reduce the conductivity of silicon

• Increase the number of holes

• Increase the number of free electrons

• Create minority carriers

The majority carriers in an n-type semiconductor are

• Holes

• Valence electrons

• Conduction electrons

• Protons

Holes in an n-type semiconductor are

• Minority carriers that are thermally produced

• Minority carriers are produced by doping

• Majority carriers that are thermally produced

• Majority carriers are produced by doping

A pn junction is formed by

• The recombination of electrons and holes

• Ionization

• The boundary of a p-type and an ntype material

• The collision of a proton and a neutron

The depletion region is created by

• Ionization

• Diffusion

• Recombination

• Answers (a) (b) and (c)

The depletion region consists of

• Nothing but minority carriers

• Positive and negative ions

• No majority carriers

• Answers (b) and (c)