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CLIL ELETTRONICA
SEMICONDUCTOR
INTRODUCTION
Some materials conduct eletric charge
better than insulators but not as well as
conductors. These materials are called
SEMICONDUCTORS
SEMICONDUCTORS
3 POINTS:
1. STRUCTURE
2. CONDUCTIVITY
3. DOPING
STRUCTURE OF THE
SEMICONDUCTORS
An intrinsic semiconductor is a
sufficiently pure semiconductor
The most used semiconductors is silicium
SILICIUM
The silicium has like symbol Si
In atoms of the semiconductors
(germanium, silicon) the valence
electrons is not free to move
through the volume of the
material, but they form a
covalent bond that alloy with of
atoms of the semiconductor in a
crystalline structure.
For effect of the breach of the
covalent bond in the
semiconductor two types of
charge carriers are originated.
Free electron are negative
electric charge while hole are
positive electric charge
CONDUCTIVITY OF THE
SEMICONDUCTORS
In semiconductors there are two types of
current. The first type of current is the
classic electric current drift current, the
second one happens for the phenomenon of
the spread electrical worker.
DOPING
There are two types of doping:
•P-TYPE
•N-TYPE
It is possible to add very small
amounts of certain impurities such as
arsenic or phosphorus which have
more electrons per atom than silicon.
In this way extra free electrons are
produced that can move and form an
electric current.
These semiconductors are
known as N-TYPE
semiconductors becuase of the
negative charge of the electrons
Another type of semiconductors is
formed by adding small quantities
of other impurities such as
aluminium or gallium which have
fewer electrons per atom than
silicon
These impurities take electrons
away from a few atoms of the
semiconductors, increasing the
number of holes.
These semiconductors are called
P-TYPE
Referring to the positive charge
associated with the holes.