X-ray absorption spectroscopy in total electron yield mode of scanning photoelectron microscopy

Total electron yield (TEY) measurement was applied to the scanning photoelectron microscopy (SPEM). The resultant image showed the thickness variation of a zinc overlayer deposited on an iron substrate with 18 nm nominal thickness. The contrast and signal-to-noise ratio of the image were much higher than those of the images obtained by the conventional SPEM. When the order-sorting aperture (OSA) located between the Fresnel zone plate and the sample was biased to +80 V relative to the sample, the contrast of the image was further improved. It also made it possible to perform microscopic X-ray absorption spectroscopy in TEY mode by preventing the unwanted photoelectrons emitted from the OSA, which can cause false TEY, from reaching the sample. Oxidized areas of the iron substrate under the thick zinc overlayer were clearly identified.