A p-n photodiode is made of a material with a band gap of 2.0 eV. The minimum frequency of the radiation that can be absorbed by the material is nearly

Options

(a) 10 x 10¹⁴ Hz
(b) 5 x 10¹⁴ Hz
(c) 1 x 10¹⁴ Hz
(d) 20 x 10¹⁴ Hz

Correct Answer:

5 x 10¹⁴ Hz

Explanation:

Eₑ = 2.0 eV = 2 x 1.6 x 10⁻¹⁹ J
Eₑ = hv v = Eₑ/h = 2 x 1.6 x 10⁻¹⁹ J / 6.62 x 10⁻³⁴ Js
= 0.4833 x 10¹⁵ s⁻¹ = 4.833 x 10¹⁴ Hz
app. 5 x 10¹⁴ Hz