Preparation and Characterization of Ta2O5Films Surface Modified by Electrostatic Self-assembly Ultrathin Films

Abstract

Ultrathin films of poly-diallyldimethylammonium chloride (PDDA)/polystyrene sulfonate (PSS) and PDDA/poly(3,4-ethylene dioxythiophene)-polystyrene sulfonate (PEDOT-PSS) were constructed on Ta2O5 films through layer-by-layer electrostatic self-assembly (ESA) method for a surface modification purpose. The self-assembly ability of PDDA/PSS and PDDA/PEDOT-PSS ultrathin films on Ta2O5 film was investigated. The results showed that the ESA ultrathin films can be constructed on Ta2O5 film surface with a layer-by-layer deposition method, and the Ta2O5 film covered with ESA film exhibited smoother surface roughness compared with Ta2O5 film without surface modification. Moreover, the electronic performance of Ta/Ta2O5/ESA films/polymer film capacitor structure was investigated. The results revealed that the capaci- tor composed of ultrathin ESA film exhibited better anti-voltage endurance ability and less leakage current, which resulted from the isolation of leakage current channel in Ta2O5 films because of surface coverage of ultrathin ESA film on Ta2O5. It also can be found that the thicker ultrathin ESA film for surface modification resulted in better anti-voltage endurance ability and higher equivalent series resistance (ESR) of Ta2O5 ca- pacitor. The further investigation confirmed that lower ESR of capacitor composed of PDDA/PEDOT-PSS ESA films because of high conductive ability of PEDOT-PSS. Keywords electrostatic self-assembly; Ta2O5; anti-voltage endurance ability; equivalent series resistor;