Which of the following is not one of the most frequently used

semiconductors in the construction of electronic devices?

• Carbon

• Germanium

• Silicon

• Gallium Arsenide

A positive ion is formed when

• a valence electron breaks away from the atom

• there are more holes than electrons in the outer orbit

• two atoms bond together

• an atom gains an extra valence electron

The difference between an insulator and semiconductor is

• a wider energy gap between the valence band and the conduction band

• the number of free electrons

• the atomic structure

• all of the above

Electron-hole pairs are produced by

• recombination

• ionization

• thermal energy

• doping

Recombination is when

• an electron falls into a hole

• a positive and negative ion bond together

• a valence electron becomes a conduction electron

• a crystal is formed

The current in a semiconductor is produced by

• electrons only

• negative ions

• both electrons and holes

• holes only

In an intrinsic semiconductor,

• there are no free electrons

• the free electrons are thermally produced

• there are only holes

• there are more electrons than holes

The process of adding an impurity to an intrinsic semiconductor is called

• doping

• atomic modification

• recombination

• ionization

A trivalent impurity is added to silicon to create

• depletion region

• a p-type semiconductor

• an n-type semiconductor

• germanium

The purpose of pentavalent impurity is to

• increase the number of free electrons

• increase the number of holes

• reduce the conductivity of silicon

• create minority carriers