The electrical conductivity of a semiconducto | vedclass

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Question

(C) The energy of the incident photon must be at least equal to the band gap energy $(E_g)$ to excite an electron from the valence band to the conduct

Vedclass · Accepted Answer

$0.5$

Vedclass · Answer

(C) The energy of the incident photon must be at least equal to the band gap energy $(E_g)$ to excite an electron from the valence band to the conduction band.$E_g = \frac{hc}{\lambda}$Given:$h = 6.63 	imes 10^{-34} \; J \cdot s$$c = 3 	imes 10^8 \; m/s$$\lambda = 2480 	imes 10^{-9} \; m$$1 \; eV = 1.6 	imes 10^{-19} \; J$Substituting the values:$E_g = \frac{6.63 	imes 10^{-34} 	imes 3 	imes 10^8}{2480 	imes 10^{-9}} \; J$To convert into $eV$,divide by $1.6 	imes 10^{-19}$:$E_g = \frac{6.63 	imes 10^{-34} 	imes 3 	imes 10^8}{2480 	imes 10^{-9} 	imes 1.6 	imes 10^{-19}} \; eV$$E_g \approx 0.5 \; eV$

The electrical conductivity of a semiconductor increases when electromagnetic radiation of wavelength shorter than $2480 \; nm$ is incident on it. The band gap in $eV$ for the semiconductor is

Similar Questions

$A$ $p-n$ junction photodiode is fabricated from a semiconductor with a band gap of $2.5 eV$. It can detect a signal of wavelength: (Given: Planck's constant $h = 6.6 \times 10^{-34} Js$,speed of light $c = 3 \times 10^8 m/s$,elementary charge $e = 1.6 \times 10^{-19} C$)

Which of the following statements is not correct in the case of light emitting diodes?

Assertion: $A$ $p-n$ junction with reverse bias can be used as a photo-diode to measure light intensity.
Reason: In a reverse bias condition,the current is small but is more sensitive to changes in incident light intensity.

Identify the incorrect statement.

The device that can detect optical signals is

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