diode types (pn junction,Zener diode).pptx

A diode is a two-terminal polarized electronic component which mainly conducts current in one direction and blocks in other direction.

Its resistance in one direction is low (ideally zero) and high (ideally infinite) resistance in the other direction.

There are two terminals of a diode. one is called cathode while the other one is called the anode.

1. Types of Diode Neeta Ukirade( Gatkal ) Pratibha College of Commerce and Computer Studies

2. CONTENTS INTRODUCTION TYPES OF DIODE P-N JUNCTION DIODE ZENER DIODE LIGHT EMITTING DIODE PHOTODIODE

3. INTRODUCTION A diode is a two-terminal polarized  electronic component  which mainly conducts current in one direction and blocks in other direction . Its resistance in one direction is low (ideally zero) and high (ideally infinite) resistance in the other direction. There are two terminals of a diode. one is called cathode while the other one is called the anode.

4. P-N JUNCTION DIODE P-N junction diodes  also called rectifier diodes are used for the rectification process. In a P-N junction diode, two layers of semiconductors materials are used . For a P-N junction diode, one layer is made of P-type semiconductor material and the other layer of N-type material. The combination of these two layers forms a junction known as the P-N junction. Thus, the name comes P-N junction diode. Representation Symbol of a Diode

5. V-I Characteristics of P-N Junction Diode Forward Biased Diode R eversed Biased Diode

6. V-I Characteristics of P-N Junction Diode

7. Zener diode Zener Diode  is recognized as a semiconductor device which allows the flow of current in both directions (forward and reverse ). It is a diode which works in reverse bias conditions. A Zener diode which is also called a Breakdown diode works in reverse bias conditions.

8. Forward Biased Diode Reverse Biased Diode V-I Characteristics of zener Diode

9. breakdowns occur for Zener Diode Avalanche Breakdown Zener Breakdown Avalanche Breakdown The phenomenon of Avalanche breakdown occurs both in the ordinary diode and Zener Diode at high reverse voltage .  If the reverse voltage is greater than 8V the avalanche breakdown happens in the Zener diode. For a high value of reverse voltage, the free electron in the PN junction diode gains energy and acquires high velocity and these high-velocity electrons collide with other atoms and knock electrons from that atoms. This collision continues and new electrons are available for conducting current thus the current increase rapidly in the diode . This phenomenon of a sudden increase in the current is called the Avalanche breakdown .

10. Zener Breakdown Zener breakdown happens in heavily doped PN junction diodes . Zener breakdown is observed in Zener diode having Vz less than 5v or between 5 to 8V. In these diodes, if the reverse bias voltages reach closer to Zener Voltage, the electric field gets stronger and is sufficient enough to pull electrons from the valance band . These electrons then gain energy from the electric field and break free from the atom. Thus, for these diodes in the Zener breakdown region, a slight increase in the voltage causes a sudden increase in the current.

11. Light Emitting Diode (LED) A light-emitting diode (LED) is a semiconductor device that emits light when an electric current flows through it . When current passes through an LED, the electrons recombine with holes emitting light in the process .  LEDs allow the current to flow in the forward direction and blocks the current in the reverse direction .

12. How does an LED work?

13. What determines the colour of an LED? The colour of an LED is determined by the material used in the semiconducting element . Aluminium alloys are used to obtain red, orange and yellow light, and indium alloys are used to get green, blue and white light . Uses of LED Used for TV back-lighting Used in displays Used in Automotives LEDs used in the dimming of lights

14. Photodiode  A photodiode is a  PN-junction diode  that consumes light energy to produce an electric current. it is also called a photo-detector, a light detector, and photo-sensor. Photodiodes are designed to work in reverse bias condition . This diode is very sensitive to light so when light falls on the diode it easily changes light into an electric current.

15. Working of Photodiode It is a  reverse-biased diode . Reverse current increases as the intensity of incident light increases . It consists of a PN junction mounted on a P-type substrate and sealed in a metallic case. The junction point is made of transparent lens and it is the window where the light is supposed to fall . when PN junction diode is reverse biased, a very small amount of reverse current flows. The reverse current is generated thermally by electron-hole pairs in the depletion region of the diode. When light falls on PN junction, it is absorbed by the junction. This will generate more electron-hole pairs.

16. Types of Photodiode PN Photodiode Schottky Photo Diode PIN Photodiode Avalanche Photodiode Applications of Photodiode Photodiodes are used in solar cell panels . Photodiodes are faster and more complex than normal PN junction diodes and hence are frequently used for lighting regulation and optical communication . Photodiodes are used in safety electronics such as fire and smoke detectors. Photodiodes are used in numerous medical applications. 

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