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Concepts Of Physics MCQ Edition [Volume 2]
Exam
Concepts Of Physics MCQ Edition [Volume 2]
Subject
Physics
Chapter
Semiconductors and Semiconductor Devices

Concepts Of Physics MCQ Edition [Volume 2] · Physics · Semiconductors and Semiconductor Devices

Determine the maximum wavelength of electromagnetic radiation...

Determine the maximum wavelength of electromagnetic radiation capable of creating a hole-electron pair in germanium. The band gap of germanium is 0.65 eV0.65 \text{ eV}.

Options

  1. A1.9×10−5 m1.9 \times 10^{-5} \text{ m}
  2. B1.9×10−6 m1.9 \times 10^{-6} \text{ m}
  3. C3.8×10−6 m3.8 \times 10^{-6} \text{ m}
  4. D1.9×10−7 m1.9 \times 10^{-7} \text{ m}

Correct answer

B. 1.9×10−6 m1.9 \times 10^{-6} \text{ m}

Step-by-step solution

The energy required to create a hole-electron pair is equal to the band gap energy EgE_g.

The maximum wavelength \lambda_\max of the electromagnetic radiation is given by:

\lambda_\max = \dfrac{hc}{E_g}

Converting the band gap energy into Joules:

Eg=0.65 eV=0.65×1.6×10−19 J=1.04×10−19 JE_g = 0.65 \text{ eV} = 0.65 \times 1.6 \times 10^{-19} \text{ J} = 1.04 \times 10^{-19} \text{ J}

Substituting the values of Planck's constant hh and speed of light cc:

\lambda_\max = \dfrac{6.63 \times 10^{-34} \times 3 \times 10^8}{1.04 \times 10^{-19}} \text{ m}

\lambda_\max = \dfrac{19.89 \times 10^{-26}}{1.04 \times 10^{-19}} \text{ m}

\lambda_\max \approx 19.1 \times 10^{-7} \text{ m}

\lambda_\max \approx 1.9 \times 10^{-6} \text{ m}
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