The GATE Grind

GATE 2019 EC – Question 45

Electronic Devices · P-N Junction and Semiconductor Devices · 2 marks · Multiple choice

The quantum efficiency ($\eta$) and responsivity ($R$) at a wavelength $\lambda$ (in $\mu$m) in a p-i-n photodetector are related by

  1. $R=\dfrac{\eta\times\lambda}{1.24}$
  2. $R=\dfrac{\lambda}{\eta\times1.24}$
  3. $R=\dfrac{1.24\times\lambda}{\eta}$
  4. $R=\dfrac{1.24}{\eta\times\lambda}$

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Correct answer: (A) $R=\dfrac{\eta\times\lambda}{1.24}$

Explanation

Responsivity is $R=\frac{\eta q}{h\nu}=\frac{\eta q\lambda}{hc}$. With $\lambda$ in $\mu$m, $\frac{hc}{q}=1.24\ \mu$m$\cdot$V, so $R=\frac{\eta\lambda}{1.24}$ A/W.