Lifetime Spectroscopy and Hydrogenation of Chromium in n- and p-type Cz Silicon

The defect parameters of isolated Cr_i and chromium-boron (CrB) pairs are reassessed by conducting lifetime spectroscopy on both n- and p-type, Cr-doped silicon samples with different doping levels, and fitting the lifetimes with the Shockley-Read-Hall (SRH) model. The uncertainty ranges of the parameters are significantly tightened through a combined analysis of the two defects with the lifetime data measured on both n- and p-type samples. Both the experimental data and the modelling results suggest that Cr_i has a greater negative impact on lifetimes in p-Si than n-Si. The possible hydrogen passivation of Cr_i in n- and p-Si is then investigated both through charge state modelling and experimentally. A general occupancy factor is applied to predict the charge states of both monovalent Cr_i and multivalent H as a function of temperature and injection level. The modelling results suggest that above 800K, both the injection and the doping become unimportant as silicon becomes intrinsic. However, despite some positive hints, the experimental evidence for hydrogenation of Cr_i is inconclusive at this stage.