INTERDIFFUSION STUDIES IN BI-BASED LAYERED SYSTEMS WITH NANOSECOND LASER-PULSES

Interdiffusion processes are induced by nanosecond laser pulses from a n excimer laser. The Bi-based systems studied are formed by a Bi layer and a Sb or Ge layer. Configurations with Bi at the surface layer or at the innermost layer are both studied. Real-time reflectivity measur ements are performed during the irradiation to determine the process k inetics and times and Rutherford backscattering spectrometry is used t o obtain the concentration depth profiles. It will be shown that there is an interfacially initiated diffusion process in the Bi-Sb system a nd that the diffusion coefficients of this system within the liquid ph ase are in the 10(-5)-10(-6) cm(2)/s range. The Bi-Ge system shows ins tead little mixing, the diffusion coefficients of the system within th e liquid phase being at least two orders of magnitude lower. The diffe rences observed when Bi is the surface layer or the innermost one are related to the different thermal responses of the system.