Selective deposition of p-type Cu_2O or conductive Cu thin film at 180°C in air on a quartz glass substrate: Development of an aqueous spray solution using two-compartment electrolysis system

摘要

A conductive Cu thin film with a thickness of 170 nm, electrical resistivity of 8.9(2) x10(-3) Omega cm and adhesion strength of 12(7) MPa was fabricated at 180 degrees C in air. The spray solutions were prepared by electrolyzing Cu electrodes in an aqueous solution of ammonium formate, and then by adding ethylenediamine-N, N, N', N'-tetraacetic acid (EDTA). The surface morphology image of resultant Cu thin film, observed by a field emission scanning electron microscope, revealed Cu grains with particle sizes of ca. 80 +/- 30 nm. It was indicated that the Cu complex containing EDTA ligand in the spray solution plays important roles to (1) provide enough amount of carbon atoms as a reducing agent for phase transition of its coordinated Cu2+ to crystalline Cu-0 and (2) prevent the product from oxidation under atmospheric O-2 during spray coating.