Using high-resolution Laplace DLTS studies it was demonstrated that three Ti-related levels (E40, E150 and H180) previously assigned to the various charge states of the interstitial Ti belonged to different Ti defects. The enhancement of the emission rates of E40 and H180 as a function of the electric field (Poole-Frenkel effect) showed that these defects were charged before they capture a majority carrier in n- and p-type Si, respectively. In contrast to previous studies, the Poole-Frenkel effect for E150 was not observed. The inconsistency was correlated with the presence of H-related defects close to E150, which could not be distinguished by using the conventional DLTS technique. The absence of the Poole-Frenkel effect for E150 indicated that the defect was an acceptor in n-type Si. The origin of the defects was considered.

A Re-Examination of the Interstitial Ti Levels in Si. V.Kolkovsky, L.Scheffler, J.Weber: Physica Status Solidi C, 2012, 9[10-11], 1996-9