Semiconductor Growth and Junction Formation within Nano-Porous Oxides

We have developed semiconductor growth techniques for the coating and filling of nanopores in ceramic-type substrates. The main idea behind this research is to use the large inner surface of ceramics as a template for the realization of semiconductor heterojunctions with extremely large interface area. As porous substrates we use lightly sintered nanocrystalline TiO2 of 5–10 μm thickness. The pore volume in these substrates is ∼50% and the average pore diameter is 30–50 nm. We are able to establish nanometer thick coatings on the inner surfaces of these substrates or — in a different technique — fill the pore volume with (100 ± 3)% efficiency. The growth techniques involve chemical and electrochemical methods from liquid solutions. Binary, ternary and, most recently, quarternary compounds of the II–VI and I–III–VI material systems were prepared.