Auger electron spectroscopy study of semiconductor surfaces: Effect of cleaning in inert atmosphere

In this paper, the authors demonstrate that Auger electron spectroscopy (AES) is an effective characterization tool in the analysis of the cleaning of semiconductor surfaces under different atmospheres. AES has several advantages for this purpose: it is nondestructive, surface specific {the analysis depth is only 4–50 Å [Childs et al., Handbook of Auger Electron Spectroscopy (Physical Electronics, Eden Prairie, MN, 1995)]}, and very sensitive to common contaminants such as carbon and oxygen. Furthermore, the authors have proven that AES allows us to describe the effectiveness of surface cleaning in a quantitative manner by comparing the peak-to-peak height of the oxygen signal for different samples. In this work, the surface cleaning of five semiconductors, namely, Si, Ge, GaAs, In_0.5Ga_0.5As, and In_0.5Al_0.5As, was investigated. The same standard HF cleaning procedure was applied in two different atmospheres, air or nitrogen. The latter was used to prevent reoxidation after cleaning. The authors found that for most of these semiconductors, the atmosphere in which the cleaning is performed has a significant influence on the results, reducing the oxygen peak-to-peak height with an extra 11.18% (average of all the semiconductors investigated) when comparing cleaning in N₂ to cleaning in air. Complementary characterization of the effectiveness of the cleaning procedure was accomplished by in situ AES, atomic force microscopy, and reflection high-energy electron diffraction for GaAs samples.