SNMS investigations of platinum-doped nanogranular tin dioxide layers

Thin platinum-doped nanogranular SnO ₂ layers are examined because of its high gas sensitivity and fast gas response to be applied in gas sensor microarrays. The nanogranular metal oxide layers were prepared from a colloidal dispersion using spin coating on silicon substrates. Field emission scanning electron microscopy (FE-SEM) investigations showed quite homogeneous layers of 20 nm particles, containing a few holes of some micron width, probably due to bubbles introduced into the layer during wet deposition. Depth resolved analysis with secondary neutral mass spectrometry (SNMS) was employed to characterize the elemental content and depth distribution of the 20 nm particle layers. A platinum content of approx. 1 at.%, homogeneously spread throughout the particles was found, as well as carbon and chlorine residues of a few atomic percent enriched at the surface of the particles.