ELLIPSOMETRY OF NON-UNIFORM ANODIC OXIDE FILMS

Tracer studies have shown that anodic oxide films grown on tantalum in dilute solutions of phosphoric acid consist of two distinct layers which, due to the movement of both metal and oxygen ions, grow simultaneously at approximately equal rates. In the present work, it was shown that ellipsometry can distinguish the two layers. The index of refraction and the thicknesses of the layers may be obtained by curve fitting. This gives a method of determining transport numbers. © 1969.