Answer to Question #119013 in Inorganic Chemistry for Yuki

Question

Silicon can be made into either a p-type or an n-type extrinsic semiconductor
by chemical doping. These can be combined to make a photovoltaic device,
which converts photons into an electrical current. Explain how this works.

Answer 1

When irradiating this system with light energy exceeding the band gap value (E>E_g, for Si the value of E_g comprises 1.1eV), the photogeneration of charge carriers (electrons and holes) takes place (at the p-n junction region). Electrons move towards the positive charge on the n-type Si whereas the holes move to the negative charge on the p-type Si. This separation of charges causes a current to flow across the junction.