Question

In LED visible light is produced by
A) Gallium Phosphide
B) Gallium Arsenide
C) Germanium Phosphide
D) Silicon Phosphide

Answer 1

Hint: The full form of LED is ‘Light Emitting Diode’. The LEDs are semiconductor devices that emit light when the current is passed through the semiconductor diode. That current passing simply means that the holes and electrons in the diode are combining. The color of the light emitted by the LEDs is determined by the material used as a semiconductor.

Complete step by step solution:
(i) LEDs are the semiconductor devices that emit photons when the current is passing through the semiconductor diode.
(ii) The semiconductors are the materials that have a bandgap of certain frequencies. If we pass the current ability to break that bandgap, the semiconductor conducts. Otherwise, it remains as an insulator.
(iii) The photons emitted by the LED’s having the wavelength concerning the bandgap of the semiconductor. Hence different semiconductor materials produce different colors of light.
(iv) Some such semiconductor materials are Indium Gallium Nitride, Gallium Indium Phosphide, Gallium Arsenide, Gallium Phosphide, etc. These materials produce colors such as red, yellow, blue, white, etc…
(v) Out of these, the visible lights are produced by Gallium Arsenide in the LED.

Hence the correct option is B.

Additional Information:
(i) LED’s composed of compound semiconductor materials. Those materials are the combination of materials in the group-V and group-III of the periodic table. Hence those elements are called III-V materials.
(ii) At first LEDs are limited in colors like red. But now we have different varieties of color LEDs. Now even we have white LEDs too. White LEDs are the complicated ones as red, blue and green lights have to be combined to form the white LED.
(iii) The LEDs are used in remote control devices, traffic signals, headlamps, etc.

Note:
The color of the light emitted by the LEDs is determined by the semiconductor material used in it. And the color is also by the band gap frequency of the semiconductor material. The invention of blue light is a revolutionary one as it consumes less current, emits less amount of heat and the invention of the blue LED leads to the discovery of a white LED.