GATE EC 2014 Set 4 — Question 18
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Electronic Devices → Optoelectronic Devices → Energy Bands
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Question
At , the band gap and the intrinsic carrier concentration of GaAs are and , respectively. In order to generate electron hole pairs in GaAs, which one of the wavelength () ranges of incident radiation, is most suitable? (Given that: Plank’s constant is , velocity of light is and charge of electron is )
Correct answer
(A) 0.42 μm < λ_C < 0.87 μm
Solution
To generate electron-hole pairs (EHP) in a semiconductor, the energy of the incident photon () must be greater than or equal to the band gap energy () of the material.The energy of a photon is given by:where:
- (Plank's constant)
- (velocity of light)
- is the wavelength of the incident radiation.
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