Remote electro-precipitation of transparent ZnO on nano-porous alumina template

Zinc oxide (ZnO) thin film was deposited onto non-conducting alumina template by remote electrochemical and precipitation method. Chronoamperometry (i.e., constant potential mode) of −0.75 V (versus Ag/AgCl) was applied to deposit compact ZnO thin film onto the honeycomb shaped pores of a nano-porous alumina membrane. Analyzing morphological observations by SEM, we observed three distinct regions: (i) conducting platinum substrate; (ii) non-conducting alumina interlayer; (iii) thin film onto alumina template. XRD structural analysis of deposited materials onto alumina template and EDX analysis of alumina layer clearly indicated the formation of ZnO thin film was formed onto non-conducting alumina template not inside of alumina template. This remote-deposited ZnO showed more compact ZnO-hexagonal structure and a little bit higher transmittance than conventionally prepared ZnO onto ITO glass. Experimental observations were further discussed via the understanding of the mechanistic origin of ZnO formation onto alumina template.