Temperature- and injection-dependent lifetime spectroscopy as a method of characterizing point defects in Si with several energy levels was demonstrated. An intentionally Co-contaminated p-type wafer was investigated by means of lifetime measurements performed at up to 151C. Two defect energy levels were required to model the lifetime curves on basis of the Shockley-Read-Hall statistics. The detailed analysis was based on the determination of the recently introduced defect parameter solution surface in order to extract the underlying defect parameters. A unique solution was found for a deep defect level located in the upper band gap half with an energy depth of Ec-Et = 0.38eV, with a corresponding ratio of capture cross-sections of k = σn/σp = 0.16 within the interval of uncertainty of 0.06 to 0.69. Additionally, a deep donor level in the lower band-gap half known from the literature could be attributed to a second energy level within the defect parameter solution surface analysis at Et−EV = 0.41eV with a corresponding ratio of capture cross sections k = σn/σp = 16. An investigation of the temperature dependence of the capture cross-section for electrons suggested that the underlying recombination process of the defect in the lower band gap half was driven by a two stage cascade capture with an activation energy of ΔE = 52meV. These results showed that temperature- and injection-dependent lifetime spectroscopy, in combination with defect parameter solution surface analysis, was a powerful method to characterize even multiple defect levels that were affecting carrier recombination lifetime in parallel.

Cobalt Related Defect Levels in Silicon Analyzed by Temperature- and Injection-Dependent Lifetime Spectroscopy. S.Diez, S.Rein, T.Roth, S.W.Glunz: Journal of Applied Physics, 2007, 101[3], 033710