The key difference between IR LED and photodiode is that the outcome of an IR LED is light, whereas the outcome of a photodiode is electric current.
IR LED is a device that can emit light in the range of IR of the electromagnetic radiation spectrum. A photodiode, on the other hand, is a semiconductor having a p-n junction that can convert photons into electrical current.
CONTENTS
1. Overview and Key Difference
2. What is IR LED
3. What is Photodiode
4. IR LED vs Photodiode in Tabular Form
5. Summary – IR LED vs Photodiode
What is IR LED?
An IR LED can be described as a device that can emit light in the range of IR of the electromagnetic radiation spectrum. These LEDs allow cheap, efficient production of IR light. This light occurs in the range of 700 nm to 1 mm wavelength.
Figure 01: IR LEDs
There are numerous uses of IR LED, including in electronics, remote controls for televisions and other electronics, and IR cameras. This device can act as a spotlight while remaining invisible to the naked eye. Moreover, we can use IR LEDs in conjunction with a number of different types of sensors, which makes them become common in machine-to-machine environments and internet of things applications.
Typically, there are IR LEDs emitting 4.5 W of flux with 850nm and 940 nm variants. These are called quad die infrared LEDs. These are known as the most powerful IR emitters.
What is a Photodiode?
A photodiode is a semiconductor having a p-n junction that can convert photons into electrical current. In this device, the p layer has a high abundance of holes which stands for positive components, while the n layer has an abundance of holes and electrons that hold negative charges.
These devices can convert light into electrical current. The source of this current comes from photons that are absorbed in the photodiode. These devices usually contain optical filters, built-in lenses, as well as large or small surface areas. Moreover, a photodiode usually contains a slower response time with an increased surface area. For example, a traditional solar cell that is useful in generating electric, solar power is a large photodiode.
Figure 02: Photodiodes
This device is similar to a regular semiconductor diode, but they are either exposed or packed with an optical fiber connection to allow light to reach the sensitive component of the device.
A photodiode can be described as a PIN structure of a p-n junction. Upon striking a photo with a sufficient amount of energy, it can cause the creation of an electron-hole pair. We call this mechanism the inner photoelectric effect. If the absorption of light occurs at the depletion region of the junction, the electric carriers sweep from the junction by the effect of a built-in electric field of the depletion region. This results in the movement of holes toward the anode and electrons towards the cathode. Then a photocurrent is produced. We can give the total current through the photodiode as the sum of the dark current.
What is the Difference Between IR LED and Photodiode?
Both IR LEDs and photodiodes are important electronic devices. They give different outcomes using different sources. The key difference between IR LED and photodiode is that the outcome of IR LED is light, whereas the outcome of a photodiode is electric current.
The below infographic presents the differences between IR LED and photodiode in tabular form for side-by-side comparison.
Summary – IR LED vs Photodiode
IR LED is a device that can emit light in the range of IR of the electromagnetic radiation spectrum. A photodiode is a semiconductor device having a p-n junction that can convert photons into electrical current. The key difference between IR LED and photodiode is that the outcome of an IR LED is light, whereas the outcome of a photodiode is electric current.
Reference:
1. “What Is Ir Led (Infrared Light-Emitting Diode)?” WhatIs.com, TechTarget, 20 Nov. 2015.
Image Courtesy:
1. “Fotodio” By Ulfbastel (CC BY-SA 3.0) via Commons Wikimedia
2. “Super-bright 5mm IR LED (25 pack) – 940nm” By Adafruit Industries (CC BY-NC-SA 2.0) via Flickr