Auger electron spectroscopy study on the Cr/Al2O3 interfacial reactions

Interfacial reactions of evaporated chromium with\(Al_2 O_3 (1\bar 102)\) surface has been studied using Auger electron spectroscopy (AES). The results reveal that the interfacial region consists of a mixture, which is a double oxide of Cr and Al or two separated oxides. After annealing, the chromium oxide and the metallic Al produced by reduction of the Al3+ ions were easily detected by AES at the interface. We suggest that the interfacial reaction occurs mainly by the charge transfer from the 3d electrons of Cr atoms to O 2p orbitals of the Al2O3 substrate. The annealing at higher temperature (≈973 K) is favourable to promote the interfacial reaction between the surface oxygen and the initial few atomic monolayers of the deposited chromium. The results also showed that the change of the relative Auger peak-to-peak height (APPH(%)) of the Cr LMM group peaks can be used as an index to identify the oxidation states of chromium at the Cr/Al2O3 interface.