Nanoscale electrodeposition of Al on n-Si(1 1 1) : H from an ionic liquid

The H-terminated Si(1 1 1)/ionic liquid interface has been imaged by scanning tunneling microscopy (STM) for the first time. Employing the ionic liquid AlCl 3 – [ C 4 mim ] + nanoscale electrodeposition of Al on Si(1 1 1) : H substrates has been investigated by in situ electrochemical scanning probe techniques at room temperature. No underpotential deposition of Al is found. Nucleation of Al begins at the Nernst potential with the formation of large islands spread all over the substrate. Under the influence of the scanning STM tip, these islands are easily disturbed which makes it difficult to image the initial stages of electrochemical phase formation. We explain this by a relatively high mobility of the islands due to the poor wetting of Al on the Si(1 1 1) : H substrate. The 3D growth of Al on Si(1 1 1) : H follows a Volmer–Weber growth mode. Scanning tunneling spectra of larger Al clusters show clearly metallic characteristics.