Surface dipole formation and non-radiative recombination at p-Si(111) surfaces during electrochemical deposition of organic layers

The surface dipole and non-radiative recombination at p-Si(111) surfaces were investigated by in-situ photovoltage and photoluminescence techniques during the electrochemical formation of a Si \ organic layer interface by reduction of different diazonium salts. The reaction rate of the radical with the negatively charged p-Si(111) surface depends on the strength and the direction of the dipole moment of the radical. The formation of the surface dipole and of non-radiative surface defects, i.e. Si dangling bonds, correlates with the reaction rate. Well passivated Si \ organic layer interfaces can be prepared and the strong dependence of the surface band bending on the effective dipole moment of the grafted organic molecules has been demonstrated. (C) 2002 Published by Elsevier Science B.V.