Structural, Optical and Electrical Properties of Nanocrystalline Cu2O Thin Films Grown by Pulsed Laser Deposition

Phase pure Cu2O is desirable as an absorber material for solar cells using ZnO electrodes because of its reported bandgap (~2.1 eV), a suitable band alignment with ZnO, and the ability to dope both n- and p-type. Pulsed laser deposition (PLD) has been used to grow Cu2O on ZnO and other substrates at low substrate temperatures and in oxygen ambient. Transmission electron microscopy and X-ray diffraction analyses showed a single phase Cu2O with (111) and (200) textures while growing at 200 C and 25 C substrate temperatures respectively.

Electrical measurements, including conductivity and electrochemical Mott-Schottky measurements, showed n-type behaviour with resistivity as low as ~3×10^-2 Ω.cm, much lower than previously reported results at ~25 C without any oxygen injection in the PLD chamber. The as grown Cu2O thin films also showed a transition from highly conductive n-type to highly resistive (~4×10^4 Ω.cm) p-type behaviour as the oxygen concentration increased.

UV-Vis diffuse reflectance spectroscopy was used to estimate the optical bandgap of the polycrystalline thin films to be in the range 2.01 -2.10 eV. The poster describes the growth, structural and electrical properties of the Cu2O films, and the properties of Cu2O solar cells grown on ZnO electrodes.