Association of FeB Pairs under Illumination

It has been found that association of iron-boron (FeB) pairs takes place during illumination of iron contaminated boron-doped silicon. The established FeB pair model is interpreted with respect to the quasi-Fermi level position, the stability condition of FeB pairs and the steady state reaction between interstitial iron, electrons and boron. At an excess charge carrier density of Δn = 5.4·1014cm-3, still 5 % of the interstitial iron associates to FeB pairs.

Iron Gettering at Slip Dislocations in Czochralski Silicon

The impact of slip dislocations on the interstitial iron distribution in as-grown CZ silicon wafers is investigated by calibrated MWPCD excess charge carrier lifetime measurements, DLTS measurements and measurements of the dislocation density. In regions of high dislocation density low interstitial iron content as well as low lifetime is observed. A linear correlation between dislocation density and interstitial iron content is found. We explain this linear correlation by the thesis that slip dislocations are 60° dislocations, which have adsorbed one iron atom at each dangling bond along the dislocation axis. Interstitial iron is gettered by slip dislocations but iron silicide, which forms along the dislocation axis, is a very strong recombination center for excess charge carriers as well. Hence, gettering of interstitial iron at slip dislocations does not increase the electrical quality of silicon.

Excess Charge Carrier Kinetics in Amorphous Silicon/Crystalline Silicon Heterojunctions

ABSTRACTBy contactless transient photoconductivity measurements it is shown that i a-Si:H films, both of standard quality films and annealed low temperature films, passivate the c-Si surface for electron-hole pairs generated in the c-Si substrate. Films deposited at low temperature without annealing do not lead to passivation of the c-Si surface. The injection of excess electrons from a standard a-Si:H film into c-Si with a time constant of a few microseconds and a rather high efficiency was observed. For an annealed 120°C a-Si:H film a slower and less efficient injection was measured, whereas an annealed 50°C a-Si:H shows no appreciable injection.