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Semiconductors
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.
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.
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.
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.
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.
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
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.
End
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