Question

Statement I When a light based $p-n$ junction is radiated with light of frequency $v$ such that $h v>E_{g}$, it produces an emf with $p$ side becoming more negative than $n$-side.
Statement II Junction field separates electron-hole pairs generated due to photon absorption and sweep them to different regions.

• A. Both Statement I and Statement II are correct and Statement II is the correct explanation of Statement I.
• B. Both Statement I and Statement II are correct but Statement II is not the correct explanation of Statement I.
• C. Statement I is correct but Statement II is incorrect.
• D. Statement I is incorrect but Statement II is correct.

Answer 1

Answer: (D)

The generation of emf by a solar cell, when light falls on, it is due to the following three basic processes generation, separation and collection (i) generation of electron-hole pairs due to light (with $h v>E_{g}$ ) close to the junction; (ii) separation of electrons and holes due to electric field of the depletion region.
Electrons are swept to $n$-side and holes to $p$-side; (iii) the electrons reaching the $n$-side are collected by the front contact and holes reaching $p$-side are collected by the back contact. Thus, $p$-side becomes positive and $n$-side becomes negative giving rise to photovoltage.