| AVS 57th International Symposium & Exhibition | |
| Applied Surface Science | Tuesday Sessions |
| Session AS-TuM |
| Session: | Electron Spectroscopies |
| Presenter: | K. Tsutsumi, JEOL Ltd., Japan |
| Authors: | M. Shima, JEOL Ltd., Japan K. Tsutsumi, JEOL Ltd., Japan T. Tazawa, JEOL Ltd., Japan |
| Correspondent: | Click to Email |
X-ray photoelectron spectroscopy (XPS) is widely used for qualitative, quantitative and chemical state analysis on various material surfaces, because XPS can obtain more stable spectra even in charged insulator surfaces than Auger electron spectroscopy. However in many cases, XPS spectra would be even distorted and shifted to high binding energy side by the positive surface charging caused by photoelectron emission. And we identify the chemical state of materials from peak position and peak shape. As a result, such a charging effect reduces the usefulness of XPS. The most widely used method for suppression of surface positive charging is to irradiate low energy electron to the sample surface. But operator should select electron flood gun conditions carefully such as accelerating voltage and the amount of the electron flux, because once the electron flux and accelerating voltage is set too high, peak shape will be distorted again and peak position turn to the lower binding energy side.
At this time, we propose a new charge compensation method that electrons irradiated from flood gun will be maintained efficiently on an insulator surface by applying positive voltage underside of insulator sample. The mechanism of this method is to accumulate excess electrons on the top of an insulator like a capacitor. Electrons maintained on insulator sample surface remove the differential positive charging, even when X-ray irradiation makes another differential charging. In addition, our experiment results shows that surface potential of insulator sample is determined simply by accelerating voltage of flood gun and it is independent of applied positive voltage for sample under the conditions that adequate electrons are supplied from flood gun. It is found that this charge compensation method has ideal mechanism; we can control not only peak shape in ideal shape but also its peak position.