Ly. Chen et al., Surface and interface properties of PdCr/SiC Schottky diode gas sensor annealed at 425 degrees C, SOL ST ELEC, 42(12), 1998, pp. 2209-2214
The surface and interface properties of Pd0.9Cr0.1/SiC Schottky diode gas s
ensors both before and after annealing are investigated using Anger electro
n spectroscopy (AES), scanning electron microscopy (SEM), and energy disper
sive spectroscopy (EDS). At room temperature the alloy reacted with SIC and
formed PdxSi only in a very narrow interfacial region. After annealing for
250 h at 425 degrees C, the surface of the Schottky contact area has much
less silicon and carbon contamination than that found on the surface of an
annealed Pd/SiC structure. Palladium silicides (PdxSi) formed at a broadene
d interface after annealing, but a significant layer of alloy film is still
free of silicon and carbon. The chromium concentration with respect to pal
ladium is quite uniform down to the deep interface region. A stable catalyt
ic surface and a clean layer of Pd0.9Cr0.1 film are likely responsible for
significantly improved device sensitivity. (C) 1998 Published by Elsevier S
cience Ltd. All rights reserved.