Surface modification of GaAs during argon ionic cleaning and nitridation: EELS, EPES and XPS studies

The cleaning and the nitridation of GaAs(1 0 0) substrates have been studied in this work by electron energy loss spectroscopy (EELS), elastic peak electron spectroscopy (EPES) and X-ray photoelectron spectroscopy (XPS). The nitridation of GaAs(1 0 0) was performed using a double differential pumping RF cell. We have studied in a first part, the surface modifications of the substrate during ionic cleaning. In a second part, we have determined the λi(E)K(E,En) curves from EELS spectra using Tougaardʹs procedure for cleaned-GaAs(1 0 0) and nitrited-GaAs(1 0 0) substrates. The thickness of the GaN overlayer was deduced from these results.