Determination of the X-Auger electron spectroscopy evolution of indium in InSb by linear and nonlinear least squares approaches

Abstract

X-ray photoelectron spectroscopy is a major and valuable chemical analysis technique that can bring a wide range of information if one takes time to carefully interpret the spectra. In particular, many metrological developments deal with the modeling of photoelectron peaks while X-Auger transitions still remain hardly exploited. Here, an innovative approach examining these spectral features in a complementary way is presented and illustrated on a concrete case dealing with chemical changes of indium in the InSb semiconductor during its air aging. Indium contains an extensive range of photopeaks along the energy scale, meaning electrons emitted from different escape depths are present on the same widescan spectrum, and, thus, information from different depths is accessible. Specifically, this study focuses on indium’s X-Auger electron spectroscopy (X-AES) transitions and decomposition to track the outer surface chemistry evolution of the InSb semiconductor. To this end, we compared linear and nonlinear least-squares approaches to decompose In M4,5N4,5N4,5 X-AES transition and demonstrate oxide growth progression. For both approaches, we applied the vectorial method (also known as the informed amorphous sample model) to retrieve the different chemical environments present during air aging. Linear and nonlinear least-squares approaches were both found to yield comparable results, with a comparative error of less than 10%. Over time, a progressive growth of the oxide layer was demonstrated, ranging from 0.3 ± 0.2 to 2.9 ± 0.2 nm using the X-AES transitions. Additionally, decomposition of the In 3d and In 4d photoelectron peaks showed a lower thickness of oxide with time due to the lesser surface sensitivity of these peaks.