Preparation of ZnO Thin Film by Electrophoretic Deposition(EPD)

Abstract

The electrophoretic deposition(EPD) of ZnO nano-sized colloids is investigated by changing the colloid number concentration, applied force, and deposition time. The change of the colloid size in a suspension was examined by the different colloid number concentrations (N = 3.98 × 10 15 , N = 3.98 × 10 14 , and N = 3.98 × 10 13 ) with an increase of the deposition time and applied forces. Deposition behavior was investigated by changing the applied fields (from DC 5 V to 50 V) and the deposition time (5 min to 25 min). The surface microstructures of the as-deposited films were investigated by SEM. The dried films were sintered from 850℃ to 1,050℃ for 2 h and then the microstructures were also explored by SEM. The agglomeration rate was enhanced by increasing the colloid number concentration of colloids. Colloid number concentration in a suspension must be rapidly decreased at higher values of the electric field. ZnO nano-sized colloids had the highest zeta potential value of over -28 mV in methanol. A homogeneous microstructure was obtained at colloid number concentration of N = 3.98 × 10 13 , applied DC field of 5 V/cm and 15 min of deposition time at an electrode distance of 1.5 cm. Under these conditions, the deposited films were sintered at 850℃ and 1,050℃ for 2 h. The results show a typical pore-free surface morphology of a uniform thickness of 400 nm under these experimental conditions.