Positron annihilation studies of the multilayer Cu-Cu3Sn system

We present a diffusion-transition model of the napping and annihilation of positrons in the grain boundaries in the form of a plane, cylinder and sphe re. This model provides the closed-form expressions for the positron lifeti me spectrum, the mean positron lifetime and the value of the S-parameter ev aluated from the annihilation line. The comparison of this model with the s tandard trapping model has been performed. In our theoretical consideration we have extended this model for the case when trapping centres for positro ns are distributed inside the grain. The validity of the model has been tes ted with positive results for study of the positron annihilation in the mul tilayer system which was produced by a sequential magnetron de sputtering o f copper and tin layers.