AVS 57th International Symposium & Exhibition
    Energy Frontiers Topical Conference Tuesday Sessions
       Session EN+TF-TuA

Paper EN+TF-TuA12
Copper Oxide Thin Films: Preparation and Modulation of Semiconducting Properties by Electrochemical Methods

Tuesday, October 19, 2010, 5:40 pm, Room Pecos

Session: Thin Films for Photovoltaics
Presenter: F. Sanz, Instituto de Biongenieria de Catalunya/CIBER-BBN, Spain
Authors: F. Caballero-Briones, CICATA-IPN/Universitat de Barcelona, Spain
A. Palacios-Padrós, Instituto de Bioingenieria de Catalunya, Spain
F. Sanz, Instituto de Biongenieria de Catalunya/CIBER-BBN, Spain
Correspondent: Click to Email
Copper oxide is a p-type semiconductor with a direct band gap of 2 eV, suitable for photovoltaic applications. In this work we present an electrochemical method to prepare p-type semiconducting Cu2O films around 100 nm thick with noticeable photocurrent response. The film properties were modulated by varying different conditions such as the time at a dissolution potential and the film doping with alkaline ions. The modification of the time of exposure to the dissolution potential allows the tailoring of the crystallinity, the band gap energy and the disorder parameter E0 and also provided elements to outline the growth mechanism of the Cu2O films that involve surface reaction, diffusion of oxygen species that react in the solid state accordingly to the point defect model, and heterogeneous deposition of Cu2O from the Cu+ ions dissolved in a chemical bath-like fashion. On the other side, the study of the behavior of different alkaline metal ions (A: Li, Na, K, Cs) present in the electrolyte used to prepare the Cu2O films lead to important results. It was observed that important amounts of the alkaline ion (around 1%) can be incorporated to the film and that are indeed electrically active impurities that modify the band gap energy probably by introducing states within the band gap in the case of Cs or by getting incorporated to the crystalline lattice for Na or Li. Changes in the optical absorption, thickness, density of carriers and in defects are related with the size of the employed ion. To complete the study, an electronic diagram of the Cu|Cu2O|Electrolyte interface was prepared by using a combination of techniques including Electrochemical Impedance and Electrochemical Tunneling Spectroscopy/Microscopy.