Cu_2O/TiO_2 nanoporous thin-film heterojunctions: Fabrication and electrical characterization

摘要

In this paper, cuprous oxide (Cu_2O)/titanium dioxide (TiO_2) diodes have been fabricated by a facile and inexpensive method for possible use in solar cells. TiO_2 nanoporous films were prepared through anodization of Ti foil and Cu_2O 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 × 10~(22) 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 V~(1/2) 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.