Thermoelectric properties of Bi$_{2}$Sr$_{2}$Co$_{2}$O$_{y}$ thin films grown by pulsed laser deposition

Epitaxial and c-axis preferred oriented oxide thermoelectric Bi$_{2}$Sr$_{2}$Co$_{2}$O$_{y}$ thin films have been deposited on LaAlO$_{3}$ (100), Al$_{2}$O$_{3 }$(0001) and fused silica substrates using pulsed laser deposition. At room temperature, the Seebeck coefficient and resistivity are of the order of 125 $\mu $V/K, 120 $\mu $V/K, 110 $\mu $V/K and 3 m$\Omega $ cm, 2 m$\Omega $ cm, 14 m$\Omega $ cm for the films on LaAlO$_{3}$ (100), Al$_{2}$O$_{3 }$(0001) and silica substrates respectively. A large negative in-plane magnetoresistance (MR) is observed in the films at low temperatures, with a MR reaching 41{\%} at 9 T and T=1.8 K in films on LaAlO$_{3}$ (100). We also observed a large bias current-dependent resistivity in the films at low temperature, which has been attributed to the suppression of spin-density-wave by electric field.