Non-aqueous electrodeposition of p-block metals and metalloids from halometallate salts

A versatile electrochemical system for the non-aqueous electrodeposition of crystalline, oxide free p-block metals and metalloids is described, and it is demonstrated that by combining mixtures of these reagents, this system is suitable for electrodeposition of binary semiconductor alloys. The tetrabutylammonium halometallates, [(NBu4)-Bu-n][InCl4], [(NBu4)-Bu-n][SbCl4], [(NBu4)-Bu-n][BiCl4], [(NBu4)-Bu-n](2)[SeCl6] and [(NBu4)-Bu-n](2)[TeCl6], are readily dissolved in CH2Cl2 and form reproducible electrochemical systems with good stability in the presence of a [(NBu4)-Bu-n]Cl supporting electrolyte. The prepared electrolytes show a wide potential window and the electrodeposition of indium, antimony, bismuth, tellurium and selenium on glassy carbon and titanium nitride electrodes has been demonstrated. The deposited elements were characterised by scanning electron microscopy, energy dispersive X-ray analysis and powder X-ray diffraction. The compatibility of the reagents permits the preparation of a single electrolyte containing several halometallate species which allows the electrodeposition of binary materials, as is demonstrated for InSb. This room temperature, 'bottom-up' electrochemical approach should thus be suitable for the one-pot deposition of a wide range of compound semiconductor materials.