Fundamental effects of hydrogen on cohesion properties of Cu/W interfaces

First principles calculation is used to investigate the thermodynamic stability of hydrogen at Cu/W interfaces and the effects of hydrogen on cohesion properties of Cu/W interfaces. It is revealed that the solution energies of H atom at the W lattice are more positive than those of H at the Cu/W interface and Cu lattice, suggesting that H atoms in the W lattice should have a tendency to diffuse into the Cu/W interface and Cu lattice. Calculation also shows that the location of interstitial H atom has an important influence on interface cohesion properties, e.g., H atom located just at the very interface area between W and Cu interface layers could dramatically decrease the interface strength of the Cu/W interface, which seems hostile to the performance and lifetime of the Cu/W interface. The derived results are in good agreement with experimental observations in the literature, and are discussed in terms of electronic structures, which could provide a deep understanding to the effects of interstitial H on various cohesion properties of Cu/W interfaces.