Heterojunctions and devices of colloidal semiconductor films and quantum dots

We present an electrical characterization of thin film semiconductor devices based on porous nanocrystalline TiO2 anatase films. It is shown that the TiO2 films can be doped, and that injecting or blocking electrical contacts can be established by metals, semiconductors, and oxides. This opens the way for the preparation of a number of all-solid-state devices. We present results on a Schottky barrier, a two-layer heterojunction on amorphous silicon, and a distributed heterojunction involving PbS quantum dots adsorbed on the internal surface of the TiO2 film. (C) 1996 American Institute of Physics.