A photodetector is made from a semiconductor | vedclass

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Question

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

Vedclass · Accepted Answer

$1703$

Vedclass · Answer

(B) The energy of the incident photon must be at least equal to the band gap energy $E_g$ of the semiconductor to excite an electron from the valence band to the conduction band.Thus,the condition for detection is $h
u \geq E_g$.The maximum wavelength $\lambda_{max}$ corresponds to the minimum energy,which is equal to the band gap energy $E_g$.$\lambda_{max} = \frac{hc}{E_g}$Given $h = 6.63 	imes 10^{-34} \, J \cdot s$,$c = 3 	imes 10^8 \, m/s$,and $E_g = 0.73 \, eV = 0.73 	imes 1.6 	imes 10^{-19} \, J$.$\lambda_{max} = \frac{6.63 	imes 10^{-34} 	imes 3 	imes 10^8}{0.73 	imes 1.6 	imes 10^{-19}} \, m$$\lambda_{max} \approx 1.703 	imes 10^{-6} \, m = 1703 \, nm$.

$A$ photodetector is made from a semiconductor $In_{0.53}Ga_{0.47}As$ with $E_g = 0.73 \, eV$. What is the maximum wavelength,which it can detect in $nm$?

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