Influence of interfacial reaction upon atomic diffusion studied by in situ Auger electron spectroscopy

Pd reaction on Si(001) substrate was studied under ultra-high vacuum using in situ real time Auger electron spectroscopy (AES). Comparison with in situ real time X-ray diffraction measurements performed on the same samples showed that the AES intensity variations observed during isothermal annealing give information concerning the kinetics of three consecutive phenomena: i) Pd2Si growth, ii) Pd dissolution in Pd2Si, and iii) Si surface segregation on Pd2Si. The kinetics related to these three phenomena allowed to determine, in the same samples, the average effective atomic diffusion during growth, and the Si and Pd self-diffusion after growth in Pd2Si. Atomic transport during growth was found to be several orders of magnitude faster than Si and Pd diffusion after growth under the same experimental conditions. This effect is assumed to be related to point-defect injection in the Pd2Si layer during growth, due to Pd–Si reaction at Pd/Pd2Si and Pd2Si/Si interfaces.