Synthesis and characterization of p-type transparent conducting CuAlO2 thin film by DC sputtering

Abstract P-type transparent conducting thin films of copper aluminium oxide were prepared by DC sputtering of polycrystalline CuAlO 2 target, which was fabricated by heating a stoichiometric mixture of Cu 2 O and Al 2 O 3 at 1375 K for 24 h. Thin films of CuAlO 2 were deposited on Si (4 0 0) and glass substrates. The sputtering was performed in Ar+O 2 (40 vol.%) atmosphere and the substrate temperature was 453 K. X-ray diffraction spectra of the films showed the peaks that could be assigned with those of the crystalline CuAlO 2 . Fourier transform infrared spectra showed CuO, AlO, OCuO bonding. UV–Vis–NIR spectrophotometric measurement showed high transparency of the films in the visible region. Both direct and indirect band gaps were found to exist and their corresponding estimated values were 3.66 and 2.1 eV, respectively. The room temperature conductivity of the film was fairly high and was of the order of 0.08 S cm −1 , while the activation energy was ∼0.26 eV. Thermoelectric power measurement indicated positive value of Seebeck coefficient and its room temperature value was +128 μV K −1 . Positive value of Hall coefficient ( R H =+16.7 cm 3  C −1 ) also confirmed p-type conductivity of the films.

[1]  K. Koumoto,et al.  Thermoelectric properties of single crystal CuAlO2 with a layered structure , 2001 .

[2]  I. Hamberg,et al.  Evaporated Sn‐doped In2O3 films: Basic optical properties and applications to energy‐efficient windows , 1986 .

[3]  P. Tarte.  Infra-red spectra of inorganic aluminates and characteristic vibrational frequencies of AlO4 tetrahedra and AlO6 octahedra , 1967 .

[4]  H. Hosono,et al.  Fabrication of transparent p-n heterojunction thin film diodes based entirely on oxide semiconductors , 1999 .

[5]  A. Draeseke,et al.  p-Type transparent thin films of CuY1−xCaxO2 , 2001 .

[6]  F. Demichelis,et al.  New approach to optical analysis of absorbing thin solid films. , 1987, Applied optics.

[7]  M. Jayaraj,et al.  Transparent p-type conducting CuScO2+x films , 2000 .

[8]  Hideo Hosono,et al.  Chemical Design and Thin Film Preparation of p-Type Conductive Transparent Oxides , 2000 .

[9]  Gregory J. Exarhos,et al.  Synthesis and characterization of transparent conducting oxide cobalt–nickel spinel films , 2001 .

[10]  Hideo Hosono,et al.  P-type electrical conduction in transparent thin films of CuAlO2 , 1997, Nature.

[11]  H. Hosono,et al.  Electronic structure and optoelectronic properties of transparent p-type conducting CuAlO2 , 2000 .

[12]  R. Wendt,et al.  Desorption of Zn from a growing ZnO:Al-film deposited by magnetron sputtering , 1997 .

[13]  Y. Kubo,et al.  Magnetoresistance in Tunnel Junctions Made of Epitaxially Grown Manganate Films with 1.6-nm-Thick Barriers , 2000 .

[14]  Hideo Hosono,et al.  Transparent p-Type Conducting Oxides: Design and Fabrication of p-n Heterojunctions , 2000 .

[15]  S. Qadri,et al.  SIZE-INDUCED TRANSITION-TEMPERATURE REDUCTION IN NANOPARTICLES OF ZNS , 1999 .

[16]  H. Cachet,et al.  Tin dioxide thin films prepared from a new alkoxyfluorotin complex including a covalent SnF bond , 2001 .

[17]  H. Hosono,et al.  SrCu2O2: A p-type conductive oxide with wide band gap , 1998 .

[18]  M. Engelhard,et al.  Infrared transparent spinel films with p-type conductivity , 2001 .

[19]  T. Ishiguro,et al.  High temperature structural investigation of the delafossite type compound CuAlO2 , 1982 .

[20]  G. Thomas.  Materials science: Invisible circuits , 1997, Nature.

[21]  K. Chopra,et al.  Transparent conductors—A status review , 1983 .

[22]  Janet Tate,et al.  p-type conductivity in CuCr1−xMgxO2 films and powders , 2001 .