Characterization of titanium hydride films covered by nanoscale evaporatedAu layers: ToF-SIMS, XPS and AES depth profile analysis

Thin titanium hydride (TiHy) films, covered by ultrathin gold layers, have been compared with the corresponding titanium films after analysis using a combination of time-of-flight SIMS (ToF-SIMS), XPS and AES, The TiHy layers were prepared under UHV conditions by precisely controlled hydrogen sorpti on at 298 K on Ti film evaporated onto a glass substrate. Both Ti and TiHy films were then covered in situ by a nanoscale Au layer, Analyses were perf ormed in separate systems after long-term exposure of the films to air. The thin gold layers covering the Ti and TiHy surfaces prevent any extensive a ir interaction with both films, allowing characterization of the bulk Ti an d TiHy layers ex situ, even after a long-term application in air. The chemi cal nature of the TiHy layers has been analysed after sputtering of the Au top layer. The high-mass-resolution positive-ion ToF-SIMS spectra disclosed only one peak at mass 49 (Ti-49(+)) for the Ti and two peaks at mass 49 (T i-49(+) and (TiH+)-Ti-48) for the TiHy film, reflecting a difference in hyd rogen concentration. Analysis of the features of the Ti Auger spectra durin g the sputter profile measurements allows the TiHy to be distinguished and characterized in the bulk region of the Au/TiHy layer. Besides TiHy, TiO an d TiOH were detected by XPS to be the main chemical compounds in the interf ace region of the Au/TiHy film. Copyright (C) 2000 John Wiley & Sons, Ltd.