Cu2O/TiO2 nanoporous thin-film heterojunctions: Fabrication and electrical characterization

In this paper, cuprous oxide (Cu2O)/titanium dioxide (TiO2) diodes have been fabricated by a facile and inexpensive method for possible use in solar cells. TiO2 nanoporous films were prepared through anodization of Ti foil and Cu2O films were deposited on it to make the diode through electrodeposition. The structural and morphological characterization was studied by X-ray diffraction (XRD) and scanning electron microscope (SEM). In electrical characterization the current–voltage (I–V) and capacitance–voltage (C–V) characteristics of the diodes were measured at room temperature. The linear behavior of C–V curve indicated that the carrier concentration was homogeneous in the film region adjacent to the equilibrium space-charge region. The thickness of the depletion region ω≅29 nm, carrier concentration N≅8×1022 m−3 and built in potential ≅0.80 V was estimated from C–V graph. The transport mechanism was due to the Poole–Frankel field effect because the experimentally obtained value of β was close to the theoretical value calculated for the Poole–Frenkel in log I against V1/2 graph. The values of several electrical parameters such as ideality factor, barrier height, and series resistances were calculated from I–V, Cheung's and Norde's functions.