Analyzing defects by temperature- and injection-dependent lifetime measurements
An intentionally cobalt-contaminated p-type wafer was investigated by means of temperature- and injection-dependent lifetime spectroscopy (T-IDLS). The detailed analysis is based on determination of the recently introduced defect parameter solution surface (DPSS) in order to extract the underlying defect parameters. Modeling these lifetime curves on the basis of the Shockley-Read-Hall (SRH) statistics required two defect energy levels. A unique solution has been found for a deep defect level located in the upper band gap half with an energy depth of E(ind c)-E(ind t)=0.38±0.01 eV and a ratio of capture cross-sections k=sigma(ind n)/sigma(ind p)=0.16 within the interval of uncertainty of 0.06 - 0.69. In addition, a deep donor level in the lower band gap half known from the literature could be assigned to a second energy level within the DPSS analysis located at E(ind t)-E(ind V)=0.41±0.02 eV with a corresponding ratio of capture cross-sections k=sigma(ind n)/sigma(ind p)=16±3. The results reveal that T-IDLS in combination with DPSS analysis is a powerful method to characterize multiple defect levels that are affecting carrier recombination lifetime in parallel.