METAL-CERAMIC ADHESION - BAND-STRUCTURE CALCULATIONS ON TRANSITION-METAL ALN INTERFACES

Tight-binding band structure calculations of the extended Huckel type are used to model transition-metal-aluminum nitride interfaces. Two di fferent interactions are found to be the determinant factors for the a dhesion of transition-metals to these ceramics. On the one hand metal- donor (surface nitrogen) interactions are found to be repulsive. These are especially important for interfaces formed with late transition-m etals since the almost filled d bands result in high energy destabiliz ing metal-ceramic antibonding orbitals. Surface aluminum atoms with da ngling bond states acting as electron acceptors toward the metal seem to be responsible for the adhesion by strong formation of metal-alumin um bonds. The basic features of adhesion to aluminum oxide described e arlier seem to be also applicable to aluminum nitride, providing thus a generalized description of the adhesion of transition-metals to cera mics.