1. P-N Junction Diode Topics covered in this presentation:
Semiconductor Basics
The Junction Diode
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2. Atomic Structure Atom is the smallest portion of an element.
Consists of nucleus (neutrons & protons) and electrons.
Same number of electrons as protons.
Element made of atoms of the same type.
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3. Semiconductors Conductors are Group 1 elements.
Semiconductors are Group 4 elements meaning they have 4 electrons in their outer shell
Number of electrons
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4. Silicon Atom Silicon has good electrical properties.
All semiconductor elements are group four materials.
Diagrams show only
the nucleus and outer shell electrons.
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5. Crystal Lattice Group 4 elements form regular crystals.
Each atom has four bonding atoms.
Does not appear to have free charge carriers.
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6. N-Type Semiconductor
Semiconductor doped with Group 5 impurity provides a free electron.
Called N-Type as it has surplus (Negative) electrons.
Very little impurity needed to provide large increase in conductivity.
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7. P-Type Semiconductor
Semiconductor doped with Group 3 impurity produces a hole in the crystal lattice.
Called P-Type as it has free holes that are Positive carriers.
Has increased conductivity.
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8. Current Flow in N- and P-Type Semiconductor
In N-Type semiconductor, electrons are repelled by negative terminal of EMF and attracted to positive terminal.
In P-Type semiconductor, holes move to the negative terminal where they collect an electron. Electrons are given up at the positive terminal to create new holes.
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9. P-N Junction Diode
P-N junction diode is an N-type region joined to a P-type region.
Electrons move from the N-region toward the P-region and holes move the other way.
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