Context:
The Hindu Explained | What are light-emitting diodes and why are they prized as light sources?
Light Emitting Diode (LED):
- Semiconductor device
- Emit light when they are activated
- Converts electrical current into optical signal
- Encapsulated with a transparent cover such that emitted light comes out.
- Made by a combination of red, green and blue light
- Making Blue LED is difficult due to risk elements in doping
- Uses– optical communication, alarm and security systems, remote-controlled operations, robotics etc.
- Types – Miniature LEDs, High-Power LEDs, Flash LED, Bi and Tri-Colour, Red Green Blue LEDs, Alphanumeric LED, Lighting LED.
- Advantages-
- Consume less power, and require low operational voltage.
- No warm-up time needed
- Emitted light is monochromatic.
- Exhibit long life.
Doping is the process of adding an impurity to an intrinsic or pure material and the impurity is called a dopant.
Diodes:
- Electronic component
- Size – about 5 mm wide.
- 2 terminals – anode (p junction) and cathode (n junction).
- Allows current to flow in only one direction.
- Achieves current flow using a p-n junction.
Semiconductors:
- Any of a class of crystalline solids intermediate in electrical conductivity between a conductor and an insulator.
- Types –
- Intrinsic semiconductors (pure semiconductors)
- Extrinsic semiconductors (adding impurity or doping)
- Applications –
- Electronic devices such as transistors, and integrated circuits.
- Power devices, optical sensors, light emitters, solid-state lasers.
- Advantages: Compactness, reliability, power efficiency, and low cost.
- Examples: Silicon, Germanium, Tin, Selenium, Tellurium, Gallium arsenide, Mercury indium telluride etc.
About India Semiconductor Mission:
- Launched in 2021.
- Ministry – Ministry of Electronics and Information Technology (MeitY)
- Nodal agency for the Schemes approved under Semicon India Programme.
- Aim – To provide financial support to companies investing in semiconductors, display manufacturing and design ecosystem.
- 4 schemes –
- Setting up of Semiconductor Fabs in India
- Setting up of Display Fabs in India
- Setting up of Semiconductors facilities in India
- Semicon India Future Design: Design Linked Incentive (DLI) Scheme
Source: The Hindu
Previous Year Question
With reference to street-lighting, how do sodium lamps differ from LED lamps?
1. Sodium lamps produce light in 360 degrees but it is not so in the case of LED lamps.
2. As street lights, sodium lamps have a longer life span than LED lamps.
3. The spectrum of visible light from sodium lamps is almost monochromatic while LED lamps offer significant colour advantages in street lighting.
Select the correct answer using the code given below.
[UPSC Civil Services Exam – 2021 Prelims]
(a) 3 only
(b) 2 only
(c) 1 and 3 only
(d) 1, 2 and 3
Answer: (c)
Explanation:
The statement 2 is not correct:
As street lights, sodium lamps do not have a longer life span than LED lamps.
Sodium lamps have an average shorter lifespan than LED lamps. High Pressure Sodium lamps tend to have a lifespan averaging 24,000 hours, whereas, LED lamps lifespan ranges from 25,000 to 200,000 hours.
