Semiconductors - ThinkChemistry

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1 Νοε 2013 (πριν από 4 χρόνια και 12 μέρες)

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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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