The recombination activity of interstitial chromium (Cri) and pairs of interstitial chromium and substitutional boron (CriBs) in crystalline Si was studied by combining temperature- and injection-dependent lifetime and deep-level transient spectroscopy measurements on intentionally Cr-contaminated n- and p-type Si wafers. Cri as well as CriBs pairs were found to be an order of magnitude less recombination active than widely assumed. In the case of Cri, a defect energy level of EC−Et = 0.24eV, an electron capture cross-section of 2 x 10-14cm2, and a hole capture cross-section of 4 x 10-15cm2 were determined. For CriBs pairs, measurements of B-doped p-type Si result in Et−EV = 0.28eV, electron capture cross-section of 5 x 10-15cm2, and hole capture cross-section of 10-14cm2. Theoretical calculations using the Shockley–Read–Hall theory showed that it depended critically upon the doping concentration whether Cri or CriBs was the more active recombination centre. Using a calibration function calculated from the defect parameters determined here, lifetime changes measured before and after thermal dissociation of CriBs pairs could be used to determine the interstitial chromium concentration in B-doped Si.

Recombination Activity of Interstitial Chromium and Chromium-Boron Pairs in Silicon. J.Schmidt, R.Krain, K.Bothe: G.Pensl, S.Beljakowa: Journal of Applied Physics, 2007, 102[12], 123701