Effect of Etching Methods on Measurement of Work Function for Gold Reference Materials

To avoid measurement errors caused by improper calibration of the equipment, it is necessary to calibrate the work function (WF) of the reference material before performing an ultraviolet photoelectron spectroscopy (UPS) test to ensure that the WF reference values are accurate and reliable. High purity gold samples with stable chemical properties and clear Fermi edge, serve as standard reference material for calibrating WF and the Fermi level. However, Au reference materials are subject to surface adsorption and contamination and must be ion etching treatment. The effect of different etching methods on the WF measurement of Au reference materials in UPS measurement was studied. The results showed that the different sputtering methods, raster scan etching and fixed-point etching, not only affected the quality of UPS spectra but also led to a decrease in WF as residual impurities in the analysis chamber environment gradually adsorbed onto the Au surface with increasing dwell time after etching. Additionally, due to the greater surface inhomogeneity after fixed-point etching, the relative error between the mean value and the standard value of the WF in the effective etching reached 10.48%. To ensure the accuracy of UPS measurements, it is recommended that WF be measured as soon as possible after etching. Raster scan etching took more time than fixed-point etching, but sample cleaning effect and spectral quality were generally better.