Consider a situation in which reverse biased current of a particular P-N junction increases when it is exposed to a light of wavelength ≤ 621 nm. During this process, enhancement in carrier concentration takes place due to generation of hole-electron pairs. The value of band gap is nearly. (a) 1 eV (b) 4 eV (c) 0.5 eV (d) 2 eV

Answer: (d). Pairs are created only when (hc)/(λ) ≥ Eg, so Eg = hcλmax. Eg = (1240)/(621) eV ≈ 2.0 eV So the answer is (d) 2 eV.

Consider a situation in which reverse biased current of a particular… | JEE Main 2021 (22 Jul, Shift 2)

Q63JEE Main 2021 · 22 JUL · SHIFT 2Easy

Special Purpose Diodes

Consider a situation in which reverse biased current of a particular P-N junction increases when it is exposed to a light of wavelength $\leq$ 621 nm. During this process, enhancement in carrier concentration takes place due to generation of hole-electron pairs. The value of band gap is nearly.

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Answer: (d)

Pairs are created only when $\dfrac{hc}{\lambda} \ge E_g$ , so $E_g = \dfrac{hc}{\lambda_{max}}$ .
$E_g = \dfrac{1240}{621}$ eV $\approx 2.0$ eV
So the answer is (d) $2$ eV.

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