describe briefly using a neccessary circuit diagram, the three basic processes which take place to generate emf in a solar cell when light falls on it.

(i) generation of e-h pairs due to light (with hν > Eg) 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.