Observations of reaction zones at chromium/oxide glass interfaces

Cr is often used in thin metallic film structures on oxide glasses since it exhibits good adhesion. The most likely explanation of the basic adhesion mechanism is the formation of a graded metal oxide layer at the interface. In general, details of the interface properties are needed to get a complet e understanding of phenomena such as adhesion. We report here observations of interface structures using spatially resolved electron energy loss spect rometry with a small probe (2 Angstrom) scanning transmission electron micr oscope. Two interfaces, evaporated Cr/alkaline earth boroaluminosilicate gl ass and sputtered Cr/barium boroaluminosilicate glass, are examined. As exp ected from the classical adhesion theory, very thin partially oxidized inte rmediate layers are seen in both samples. However, a 5 nm Cr diffusion laye r is also found in the evaporated Cr/glass system (without heat treatment), but it appears absent in the sputtered Cr glass system (with heat treatmen t). This difference suggests that the mechanisms of the adhesion of Cr to o xide glass are dependent on interface history. (C) 2000 American Institute of Physics. [S0021-8979(00)05308-1].