Photodiode

INTRODUCTION

A photodiode is a PN-junction diode that uses light energy to generate electrical energy. It is sometimes called a photo-detector, a light detector, and a photo-sensor. These diodes are designed specifically for operation in receding conditions, meaning that the P-side of the photodiode is connected to the negative battery terminal, and the n-side is connected to the positive battery terminal. 

This diode is very sensitive to light so when light falls on the diode it easily converts        light into electrical energy. The solar cell is also called the large photodiode because it converts   solar energy into electrical energy. However, the solar cell only works in bright light.

WHAT IS PHOTODIODE

 A photodiode is a single type of light detector, used to convert light into current or voltage based on device operating mode. Includes optical filters, built-in lenses, and overhead areas. These diodes have a slow reaction time as the surface area of ​​the photodiode grows. Photodiodes are similar to conventional semiconductor diodes, but may be visible so that light can reach the soft part of the device. 

Several diodes intended for direct use as photodiodes will also use a PIN junction in some way rather than a conventional PN junction. Some photodiodes will look like light emitting diodes. They have two terminals from the end. The lower end of the diode is the terminal cathode, and the lower end of the diode is the anode terminal. For the anode and cathode sides. Under forward mode, the normal flow will flow from the anode to the cathode, following the diode signal arrow. Photocurrent flows backwards.

TYPES OF PHOTODIODE

Although there are many types of photodiodes available on the market, they all work on the same basic principles, though some are enhanced by other effects. The function of different types of photodiodes works differently, but the basic functionality of these diodes remains the same. The types of photodiodes can be classified based on their structure and functions as follows –

 1.PN Photodiode

 2.Schottky Photodiode

 3.PIN Photodiode

 4.Avalanche Photodiode

PN PHOTODIODE

The first advanced type of photodiode is the PN type. Compared to other models, its functionality is not improved, but at the moment, it is used in several programs. Photodetection occurs mainly in the area of ​​diode depletion. This diode is very small but its sensitivity is not great compared to others.

PIN PHOTODIODE

Currently, the most widely used photodiode is the PIN type. This diode collects brightly illuminated photographs compared to the conventional PN photodiode because the wider inner space between the P and N regions allows more light to be collected, and in addition, also provides lower power.

AVALANCHE PHOTODIODE

This type of diode is used in bright areas due to its high gain levels. Produces high levels of noise. So this technology is not suitable for all applications.

SCHOTTKY PHOTODIODE

The Schottky photodiode uses the Schottky diode, and incorporates a small diode junction which means, there is a small junction for it, working at high speeds. Therefore, this type of photodiode is commonly used in high-bandwidth (BW) communication systems such as fiber-optic.

MAIN FEATURES

• The linearity of the diode is good with respect to incident light
• Noise is low.
• The response is wide spectral
• Rugged mechanically
• Lightweight and compact
• Long life

Requirements for photodiode making and electromagnetic spectrum wavelength range include the following

For silicon materials, the wavelength range of the electromagnetic spectrum will be (190-1100) nm.

For Germanium materials, the wavelength range of the electromagnetic spectrum will be (400-1700) nm.

With Indium gallium arsenide material, the wavelength range of the electromagnetic spectrum will be (800-2600) nm

With Lead (II) sulfide material, the wavelength of the electromagnetic spectrum will be <1000-3500) nm

For Mercury, the cadmium material Telluride, the wavelength of the electromagnetic spectrum will be (400-14000) nm

WORKING OF PHOTODIODE

The principle of operation of a photodiode is that, when a photon of sufficient force strikes a diode, it forms an electron-second hole. This mechanism is also called the internal photoelectric effect. If the absorption arises from the reduction circuit assembly, then the carriers are removed from the assembly by the built-in electric field of the reduction zone.

Therefore, the holes in the circuit go to the anode, and the electrons move to the cathode, and a photocurrent will be formed. The total current per diode is the total amount of light and photocurrent. The missing current should therefore be reduced to increase device sensitivity.

CONCLUSION

Photodiodes are optoelectronic devices that vary in type and use and can be customized for use on almost any electronic device. They can be used with infrared light sources such as LED, neon, fluorescent and laser light. And cheaper than most light emitting diodes.