This document discusses diodes, including their physical structure, operation under forward and reverse bias, types of diodes, and applications. A diode is an electronic component that allows current to flow in only one direction. It consists of a P-N junction formed by joining a P-type and N-type semiconductor. Under forward bias, the depletion region narrows and current flows easily. Under reverse bias, the depletion region widens and prevents current flow. Zener diodes have a thin depletion region and allow current when the reverse bias voltage exceeds the zener voltage. Diodes are commonly used as rectifiers and voltage regulators.

1. D DIODE
Parvathy S Ra
S1EEE
54

2. DIODE IS AN ELECTRONIC
COMPONENT WHICH
ALLOW CURRENT ONLY IN
ONE DIRECTION.

3. CONTENTS
• INTRODUCTION
• PHYSICAL STRUCTURE OF A DIODE
• FORWARD BIAS
• REVERSE BIAS
• TYPES OF DIODE AND APPLICATION
• ZENER DIODE

4. INTRODUCTION
• Invented by John Ambrose
fleming in 1904.
• Fleming constructed with 2
electrons in the form of a
vaccum tube.
• Commonly used in dc power
supply units as rectifiers and
voltage
regulators,clippers,clamper
in circuits.
• Comes in different shapes
and sizes.

5. PHYSICAL STRUCTURE OF A
DIODE

7. •Formed by joining two equivalently
doped P-type and N-type
semiconductor.
•At the point of contact of the p
type and N type region, the holes
in the P type attracts electrons in
the N type material.
•Electron diffuses and occupies the
holes in the p type material.

9. •This creates a layer of negative
ions near the junction in P type
material.
•These two layers of positive and
negative ions form the depletion
region.
•The term “depletion” refers to the
fact that the region near the
junction is depleted of their

11. FORWARD BIAS
• In this state, the negative of battery pushes the
free electrons against the barrier from n to p-
region while positive of battery pushes holes
against barrier from p to n-region.
• Width of the depletion region is less.
• Barrier potential is less.
• If the applied voltage is increased at a
particular value depletion region becomes
narrow.
• Large number of majority carries constitute a
current called forward current.

13. REVERSE BIAS
• In the reverse biasing of a diode, the negative of
battery attracts the holes in p-region and positive
of battery attracts the electrons in n region away
from the junction.
• Depletion region is wide.
• Increases barrier potential.
• Resistance is high and diode remains non co
operative in this state.
• Behaves like an open switch.

14. TYPES OF DIODE
AND
APPLICATIONS

17. WORKING OF A ZENER DIODE
• Diode is made up of heavily doped semiconducter
material.
• The depletion region of the zener diode is very thin.
• Unbiasing condition of zener diode.
• No current flow ,electrons remain in valence band.
• Reverse bias condition in zener diode, supply voltage is
equal to zener voltage it starts conduction.
• Intensity of electric field increases across depletion
region.
• Transfer of electrons in valence bands to conduction
band.

18. CONCLUSION
• In this presentation, I have explained about the
topic Diode by providing full details on it. This
project also emphasizes on main ideas related
to the topic.
• I took the ideas and researched about this
topic from the websites and some the
bibliography. I wish this will be a useful and
the knowledgeable.

19. THANK
YOU