Physical and chemical applications of photodoping in electrodeposited cuprous oxide thin films.

by Coridan, Robert; Lowe, James M.

External fields can be used to regulate the morphol. and chem. properties of electrochem. synthesized materials. Examples include emergent morphol. patterns in electrodeposited thin films or plasmon-induced shape control in nanocrystals. These illustrate the principle of phototropism, where the coaction of light absorption and carrier generation can induce controllable variations in the material as it grows under illumination. Here we describe the photoelectrodeposition of photocathodic cuprous oxide (Cu2O). Illuminating the growing film with photon energies larger than the band gap of Cu2O results in nanoscale morphol. changes in the structure of thin films and intrinsically dopes the material during growth. The result is a 'black' Cu2O film that is chem. distinct but crystallog. identical an ordinary film grown in the dark. The flat band potential of the film is controlled by the growth illumination intensity and the photodoping is reversible under thermal oxidn. We explore the nature of the intrinsic dopant as evidenced by the emergence of nanocryst. Cu metal inclusions in the Cu2O matrix. Finally, we explore the potential of for this effect to be used in new semiconductor heterostructures prepd. by light-directed fabrication. A09.