Impact of electric fields on the Co electrodeposition onto n-Si(111):H Surfaces

The influence of electric fields on the Co electrodeposition onto n-Si(111):H surfaces has been studied using a scanning tunneling microscope (STM). The STM allows for the generation of an electric field in the tunneling gap and directly at the n-Si(111):H surface. Localised Co electrodeposition has been rendered possible at the lateral position of the STM tip in tunneling contact at an electric field of approximately 0.6 V/nm at the n-Si(111):H surface. No Co electrodeposition onto n-Si(111):H has been observed at the same experimental conditions, but without an applied electric field. The effect can be attributed to a local polarisation of H-Si bonds at the n-Si(111):H surface by the applied electric field lowering the activation barrier for the Co electrodeposition onto n-Si(111):H. The observed effect of an electric field appears to be the origin for the required overpotential in the macroscopic electrodeposition of Co onto n-Si(111):H.