Molibdenum contamination in silicon 1. Molibdenum detection by lifetime techniques

In this work the use of lifetime techniques in the presence of a non-uniform profile of recombination centers is discussed. It is shown that measurements with different probing depths can be used in order to obtain information about the in-depth distribution of recombination centers. Molibdenum was chosen for this study, because it is probably the most common slowly diffusing contaminant. In this study, it is also shown that molibdenum inactivation does take place by segregation at the wafer surface. The evidence from lifetime techniques is confirmed by TEM analyses, revealing tiny molibdenum clusters at the wafer surface.