The combination of Auger electron spectroscopy (AES), scanning electron microscopy (SEM) and angle resolved X-ray photoelectron spectroscopy (ARXPS) has been applied to the analysis of the distribution of elements at the surface region of electrochemically etched tungsten tips and the determination of the thickness of a layer with oxygen and carbon contamination. Auger line profiling revealed a homogeneous distribution of oxygen and significant enrichment of carbon on the W tip between 0 and 1.5 μm from the top. The thickness of the contamination layer on various W materials, electrochemically etched, was found to be 1.35±0.15 nm as measured using ARXPS, and was estimated to be about 1–3 nm as measured by AES.
Lisowski, W. F., van den Berg, A. H. J., van den Berg, A., Hanekamp, L. J., Hanekamp, L. J., & van Silfhout, A. (1992). Distribution and thickness of the surface contaminations on STM tungsten tips, studied by AES/SEM and ARXPS. Microchimica acta, 107(3-6), 189-196. https://doi.org/10.1007/BF01244472