Seminar: XPS as a Probe of Hidden Electric Information: The Puzzle of Spontaneous Oscillations in ZnOS
X-ray photoelectron spectroscopy (XPS) has become a promising template for non-contact chemically resolved electrical measurements (CREM),1,2 a technique offering unique capabilities with respect to any of the standard electrical tools. In this talk I will describe some of these exciting capabilities and focus on a recent study: CREM of a thin ZnOS layer on gold. Exotic phenomena in the response of this system to light illumination were revealed. First, double triggering of its current output was demonstrated; a feature associated with a buffer-like level of trap states. Second, spontaneous current oscillations were found to emerge, restricted to a narrow range of the input signals. The latter effect presents a large number of consistent and well understood experimental evidences, however a question is still left about the atomistic mechanism at the basis of these oscillations.