2. Semiconductors

3. What Is A Semiconductor? A semiconductor is a substance that has a lower conductivity than a metal and a higher conductivity than a non-metal. They appear at the divide between metals and non-metals on the periodic table, for example silicone and Germanium. There are two types of semiconductor, p type and n type.

4. P type Semiconductors P type semiconductors are made by adding an atom with one less outer electron than the other atoms in the surrounding network. This means that the ‘impurity’ atom creates a hole where an electron would normally be, leaving room for electrons to move into allowing for electric current to flow.

5. N type Semiconductors N type semiconductors are made by adding an atom with one more outer electron than the other atoms in the surrounding network. This means that the ‘impurity’ atom supplies an extra electron to carry charge.

6. Conduc(k)tivity As a semiconductor’s heat increases so to does its electrical conductivity. Also a semiconductor’s conductivity increases with exposure to light.

7. Uses of the Semiconductor Can be used in photovoltaic cells, a vital component in solar cells. Commonly used to make electronic devices such as transistors, diodes and integrated circuits.

8. Questions From the Past The electrical conductivity of the semiconductor gallium arsenide increases on exposure to light. What name is given to this phenomenon? Answer: Photoconductivity

10. Another Question An example of a p-type semiconductor is silicon doped with A carbon B arsenic C aluminium D phosphorus D is the answer.

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