Electronic properties of titanium in boron-doped silicon analyzed by temperature-dependent photoluminescence and injection-dependent photoconductance lifetime spectroscopy
Temperature-dependent lifetime spectroscopy allows for the determination of defect parameters (like ratio of the carrier capture cross sections and energy level) of pointlike defects in silicon. This necessitates reliable measurements of the low-level injection excess carrier lifetime. Photoluminescence-based measurement techniques have been shown to be ideal for this kind of measurements at room temperature, being immune to several measurement artifacts such as minority carrier trapping or depletion region modulation. In this article it will be shown how the effect of photon reabsorption influences the temperature-dependent photoluminescence measurements and how this can be accounted for using a theoretical model based on the generalized Planck equation. An intentionally titanium-contaminated silicon sample is investigated by means of temperature-dependent photoluminescence and injection-dependent photoconductance lifetime spectroscopy. Defect parameters of two independent recombination centers will be presented, which titanium introduces into the silicon band gap. One defect level at E-C-0.24 eV agrees very well with a level found via deep-level transient spectroscopy measurements while another level at E-C-0.49 eV could be measured for the first time using the advanced lifetime spectroscopic approach presented here.