Interface structure and work function of W-Cu interfaces

First principles calculation reveals that W-Cu interfaces have high interface strength when the number of overlayers is less than 2, and that (111)Cu/(110)W and (110)Cu/(110)W interfaces with one overlayer are both energetically favorable with big negative interface energies. Calculation also shows that negative interface energy serves as the driving force for interdiffusion and alloying of immiscible W and Cu, and that interface orientation fundamentally induces different behaviors of work functions of W-Cu interfaces. The calculated results agree well with experimental observations, and clarify two experimental controversies regarding interface stability and work function of W-Cu interfaces in the literature.