A p-n photodiode is fabricated from a semiconductor with band gap of 2.8 eV . Which of the following wavelength it can detect?

Question

A p-n photodiode is fabricated from a semiconductor with band gap of 2.8 eV . Which of the following wavelength it can detect? (A) 950 nm (B) 820 nm (C) 580 nm (D) 440 nm

Tardigrade Admin · Accepted Answer

Given, E=2.8 eV =2.8 × 1.6 × 10-19 Energy E=(h c/λ) ∴ λ=(6.6 × 10-34 × 3 × 108/2.8 × 1.6 × 10-19) =440 × 10-9 m =440 nm

Q. A $p - n$ photodiode is fabricated from a semiconductor with band gap of $2.8 e V$ . Which of the following wavelength it can detect?

950 nm

820 nm

580 nm

440 nm

Given, $E = 2.8 e V$
$= 2.8 \times 1.6 \times 1 0^{- 19}$
Energy $E = \frac{h c}{λ}$
$∴ λ = \frac{6.6 \times 1 0 ^{- 34} \times 3 \times 1 0 ^{8}}{2.8 \times 1.6 \times 1 0 ^{- 19}}$
$= 440 \times 1 0^{- 9} m = 440 nm$

Q. A p−n photodiode is fabricated from a semiconductor with band gap of 2.8eV . Which of the following wavelength it can detect?