Superstrong direct adhesion of Au, Ag, and Cu electrodes to oxide substrates via interfacial engineering

Electronic and optoelectronic devices usually include metal electrodes, particularly Au, Ag, and Cu layers, owing to their excellent conductivities. Achieving robust adhesion between these coinage metal electrode layers and various oxide substrates remains a considerable challenge due to the weak O affinities of coinage metals, specifically that of Au. Direct contact between the electrodes and substrates without electronically deficient intermediates, such as Ti and Cr adhesive layers, is highly desirable for improving device performance. In this study, we numerically hypothesize and experimentally confirm that the incorporation of excess atomic O interstitials into the Au/oxide interfaces and Au surfaces substantially enhances the direct adhesion between the Au electrodes and oxide substrates, while preserving the uniqueness of the Au electrodes. Our findings highlight the role of O interstitials as chemical bridges between Au electrodes and oxide substrates in film structures. The unprecedented direct adhesion of the Au electrodes to oxide substrates was detected (exhibiting enhanced adhesion strength from 0.02 to > 50 N); this adhesion strength is substantially higher than those (< 20 N) afforded by conventional techniques. The proposed strategy was extended to Cu and Ag electrodes with compelling evidence using atomic N and O interstitials. The superstrong adhesion of these metal film electrodes was realized without compromising the metal electrode integrity, paving the way for advancing the integration of metal electrodes into devices.