Total-Electron-Yield Measurements by Soft X-Ray Irradiation of Insulating Organic Films on Conductive Substrates

The photocurrent (sample current) of insulating 0.7-μm thick polyethylene terephthalate (PET) films on conductive substrates (C, Au, Cu) was clearly measured through the substrates during soft X-ray irradiation on the PET films. X-ray absorption measurements of the PET/conductive-substrates using the total-electron-yield (TEY) method by measuring sample current easily provide the X-ray absorption spectra (XAS) of PET films, which are independent of the substrates. From additional X-ray absorption measurements using self-standing PET/Au and Au/PET-films, I-V measurements, and thickness-dependent sample current measurements, it can be confirmed that electrically conductive paths form in the insulating PET film in thickness direction along the soft X-ray beam trajectory. Such phenomena enable easy and simple TEY-XAS measurements of insulating μm-order-thick samples.