Photoelectrodeposition of thin Co films on p-Si from sulfate solutions

The electrodeposition of thin layers of Co on hydrogen terminated p-Si substrates from sulphate solutions was analyzed by means of cyclovoltammetry, impedance and atomic force microscopy (AFM). The reduction of Co2+ on p-Si involves the discharge of photogenerated electrons at the conduction band edge and/or surface state levels at potentials more negative than the flat band condition. The diffusion controlled growth of Co films is characterized by the advance of a smooth front with a constant root mean square (rms) roughness of 6 to 7 nm. The deposition mechanism was analyzed by means of the Power Spectral Density of the AFM images. Then, the quality of the interface Si/Co was determined by its quasi-ideal rectifying behaviour with a Schottky barrier Φ = 0.57 eV.