Photo Diode Working Explained

Photodiodes are light sensitive elements that can be used in devices. It is a photoelectric device that transforms light into an electrical current. Photodiodes are semiconductor devices that act as light-to-electricity converters. In this topic, we also introduce the basic properties of the photodiode along with its working and working principle.

The photodiode is a semiconductor junction photoelectric device or photodetector. It is a device that detects light. A photodiode consists of an extremely thin p-type silicon wafer, called a substrate. The substrate has a thin layer of oxide at the surface, which allows light to enter the sensor.

Fundamental Importance of Photodiodes

Photodiodes are the first building block of photovoltaics and light-emitting diodes (LEDs). They are therefore of fundamental importance for a variety of scientific and technological applications, ranging from medicine, biology, chemistry to engineering and architecture.

Components of Photodiodes

The photodiode is an optical device for detecting light. It is a diode, one of two important electronic components: the diode and the transistor. The diode transmits light but is also sensitive to light. A photodiode is made of two layers of material separated by a layer of silicon.

Types of Photodiodes

Photodiodes can be classified by their sensitivity. There are four kinds of Photodiodes.

PN Photodiode

A PN Photodiode is a diode in which the P and N regions are made from a single piece of N-doped silicon. The PN junction is created by a metal contact that is placed very close to the surface so that a few monolayers of silicon are removed from the surface.

With the PN photodiode, in a dark box with your eyes closed, you can detect a light source, like the sun or a light bulb in another room.

PIN Photodiode

Photodiode (PIN) is a light-sensitive device, which can be used to detect changes in brightness (light intensity) and can be used to measure the intensity of light or infrared.

PIN Photodiode works on the principle of photon-electron conversion. The PIN Photodiode consists of two p-n junctions which are formed by depositing an intrinsic, n-type, semiconducting material (typically germanium or silicon) over an undoped, intrinsic, semiconducting material (typically gallium arsenide or indium phosphide). Two depletion regions form under the two p-n junctions

Avalanche Photodiode

Avalanche Photodiode is used in the detection of electrical signals in many areas of engineering. Avalanche photodiode is a photodiode that can operate at room temperature, and it is the basic component of many detectors used in optical communication, radiation detection, and radiation dosimetry. Avalanche photodiodes (APD) are semiconductor photodetectors characterised by extremely high photosensitivity. They are used in a variety of applications, such as astronomical instruments, space- and time-resolved imaging, and optical communications.

Schottky Photodiode

A Schottky photodiode is generally used in a photodiode amplifier. The photoelectric effect occurs when light strikes a semiconductor surface. The impact causes electrons (negative charge) to be ejected from the surface. When a forward bias is applied (light is shining on the diode), the current increases as electrons accumulate on the anode. A Schottky Photodiode is a device for detecting electromagnetic radiation, specifically light, in the form of solar or radio waves.

Properties of Photodiodes

1. The photodiode is the most basic element in a photodiode array. The diodes can be made on different substrates, with different band gaps, and doped with different impurities. For this reason, it is the sensor of choice for many IR and visible detectors.

2. Photoelectric photodiodes are semiconductors whose conductivity depends on the intensity of incident light.

3. Photodiodes are diodes that allow current to pass through them in only one direction. If there is a voltage difference of greater than 1 volt across a diode, the diode will allow the current to pass only in one direction.

Uses of Photodiodes

1. They are used as light detectors in optoelectronic circuits, such as cameras, video recorders, and other light sensitive devices.

2. Photodiodes are used in a variety of devices, including sensors, light-based communication systems, medical equipment, and imaging devices.

3. Photodiodes are one kind of photodetectors, that is they detect light, which is widely used in many devices including photoresistors, phototransistors, photodiode arrays, photodetector arrays, p-n junction type phototransistor, and avalanche photodiode (APD) arrays.

4. They are used as optical detectors for electromagnetic radiation.

Working of Photodiodes

A photodiode is an electronic solid-state device that changes light into electricity by absorbing it. A photodiode can be composed of many materials that have been doped or impregnated with dopants, such as silicon, germanium, gallium-arsenide, and cadmium-telluride. Using a photodiode we can measure current from a photoresistor. The resistance changes as the light changes, and we can measure the current by measuring the resistance.

An electromagnetic wave of any form is a disturbance of the electromagnetic field. When light passes through a transparent medium, such as glass or plastic, it is refracted. As that wave passes through the substance, the particles oscillate back and forth in a regular pattern. The amplitude of the oscillation is proportional to the amount of light that passed through the substance, which is measured in photons.

When light shines on it, the p-n junction absorbs photons, which excite electrons from the valence band into the conduction band, increasing the electrons. When the electron returns to the valence level, it leaves a hole that can be filled by a conduction electron.

The photocurrent is proportional to the difference between the number of photons in the active volume and in the non-active volume.

Conclusion

A photodiode is a semiconductor device that is in general composed of a p-n junction, a semiconductor material with a wide bandgap. In its simplest form, a photodiode consists of a p-type semiconductor with a light-receiving surface, and an n-type semiconductor with a light-emitting surface separated by a barrier that restricts the transfer of electrons. The two semiconductors are connected so that the electron-hole pairs are created by absorbed photons.