A method is presented for the electrochemical deposition of organic monolayers on Si(111) surfaces from aqueous solutions of diazonium salts. The deposition process at fixed cathodic potential is in-situ monitored by current, photvoltage and photoluminescence measurements. The process is based on the formation of radicals from diazonium ions and reaction of the benzene radicals with the Si surface. There is a self-limitation in current density during the deposition of benzene compounds on atomically flat H-terminated Si(111). Thick organic layers are deposited on atomically rough H-terminated and on oxidized Si(111). The self-limited deposition on oxide free Si(111) can be divided into two phases, one Si adsorption site limited and one diffusion limited. Diffusion constants are estimated from current transients, with values ranging between the diffusion constant of organic molecules in solids and solutions. Photoluminescence measurements show no increase in the number of non-radiative recombination centers during the exchange of Si-H by Si-C bonds. There is a linear correlation between the band bending at the Si surface measured by photvoltage and the value of the molecule dipole moment calculated by density functional theory. An ultra-clean grafting is possible via a gettering effect for benzene compounds changing the direction of the dipole moment during the transformation from the diazonium ion to the radical and molecule.    «

A method is presented for the electrochemical deposition of organic monolayers on Si(111) surfaces from aqueous solutions of diazonium salts. The deposition process at fixed cathodic potential is in-situ monitored by current, photvoltage and photoluminescence measurements. The process is based on the formation of radicals from diazonium ions and reaction of the benzene radicals with the Si surface. There is a self-limitation in current density during the deposition of benzene compounds on atomic...    »