Interaction of Chromium Atoms with Dislocations and as-Grown Vacancy Complexes and its Impact on the Electronic Properties of FZ-Si

By using deep level transient spectroscopy (DLTS) and light beam induced current (LBIC) the behavior of chromium atoms in float-zone n-Si in the presence of dislocations and as-grown vacancy complexes has been investigated. It was found that reactions of interstitial chromium atoms with dislocations and with as-grown nitrogen-vacancy complexes reduce significantly the nucleation barrier for the formation of chromium-silicide precipitates so that nearly all Cr atoms are collected into the precipitates even in quenched samples. These nano-precipitates are very active in electron-hole recombination and give a very broad DLTS signal related to deep donor electronic states in the bandgap of silicon.