Abilities of elastic peak electron spectroscopy in the field of thin films growth investigation: Au on Al and Al 2O 3

Abstract

Since the electron elastic reflection coefficient depends on the target atomic number, elastic peak electron spectroscopy (EPES) may be employed to monitor inhomogeneous thin films growth. In frame of this work, growth of gold on aluminium and alumina was studied using an originally designed EPES spectrometer at various temperatures. To optimise the experimental parameters, the elastically reflected electron current from a gold sample normalised to that one from an aluminium sample was measured as a function of the incident energy. A maximum at the energy of 550 eV was found. It corresponded to the result of an independent EPES measurement on gold carried out using another spectrometer. Then gold was grown on aluminium and the elastically reflected electron current was followed. The signal intensity vs. deposition time curve exhibited equidistant break points indicating the layer-by-layer growth mode. The saturation value was reached as soon as three atomic layers of gold had been completed. This result is in a good agreement with a Monte Carlo simulation confirming an excellent surface sensitivity of EPES. Final experiments were performed on gold grown on alumina. The EPES signal intensities raised fractionally again. It proved the layer-by-layer growth mode of gold on alumina and applicability of EPES to its investigation.