XPS INVESTIGATIONS OF THE INTERACTIONS OF HYDROGEN WITH THIN-FILMS OFZIRCONIUM-OXIDE .1. HYDROGEN TREATMENTS ON A 10-ANGSTROM THICK-FILM

Interactions of hydrogen with the interface formed between ZrO2 and zi rconium suboxide (ZrOx, x < 2) were studied on a 10 Angstrom zirconium oxide film prepared on gold foil for X-ray photoelectron spectroscopy (XPS) analysis. This film was subject to a set of sequential treatmen ts. Reaction with II, gas at 2 mbar pressure and room temperature indi cates that the ZrO2/ZrOx interface appeared to undergo a redox-type re action and convert to a new ZrO2/ZrOy (x < y < 2) film. Heating this s tructure at 300 degrees C in a 10(-9) mbar vacuum (residual gas domina ntly H2O) resulted in more ZrO2 in the outer region and less ZrO, in t he subsurface. By contrast, when this film was treated with a hydrogen plasma, XPS showed enhanced formation of -OH groups and complete conv ersion to the ZrO2-like form. On heating to 300 degrees C, this unifor m film regenerates the ZrO2/ZrOy interface structure, apparently with desorption of H2O.