The Reaction Kinetics of Iron‐Boron Pair Formation and Dissociation in P‐Type Silicon

Abstract

The reaction kinetics of iron-boron formation and dissociation in p-type silicon were investigated. The results indicate that the reaction kinetics depend strongly on the relative position of the ionization energy of interstitial iron and the Fermi level. At temperatures below a transition temperature where the ionization energy of interstitial iron is equal to the Fermi level, the iron-boron pairing reaction is dominated by the electrostatieally enhanced recombination process between interstitial iron and substitutional boron. This pairing reaction is limited to the iron diffusion which may be described by the diffusion coefficient correlated by WeberJ At temperatures above the transition temperature, the concentrations of ionized and neutrally charged interstitial iron species are in equilibrium. The equilibrium reaction, which is facilitated by thermally excited electrons, gives rise to a deionization of the charged interstitial iron species and in turn causes the dissociation of the iron-boron pairs. ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 129.93.24.73 Downloaded on 2015-03-17 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 129.93.24.73 Downloaded on 2015-03-17 to IP

Contamination of silicon by iron at temperatures below 800 °C

“…Figure 2 shows lifetime at an injection level of 0.5 N A versus time after dissociation of the FeB pairs in a sample contaminated at 656 °C. The experimental results are very well described by a model based on the kinetics of iron diffusion and the binding energy of the FeB defect 14 described elsewhere 15. This confirms that the intense illumination acts only to dissociate the FeB defect.…”

“…An initial lifetime measurement was made immediately. A final lifetime measurement was made at least 24 hours later, which for the conditions investigated is sufficient time for complete reassociation of the FeB defect 14.…”

Passivation Effects on Low-Temperature Gettering in Multicrystalline Silicon

“…SiN x passivation remains on the Set I samples during annealing. After each annealing step, samples were stored in the dark for ࣙ 36 h to ensure complete reassociation of FeB defects [23], prior to recharacterization by QSS-PC and PL imaging.…”

Enhanced gettering of iron impurities in bulk silicon by using external direct current electric field

“…The dissociation of Fe ϩ i -B Ϫ s pairs would release Fe ϩ i as isolated interstitials 29,30 that could diffuse to the surface region. 31 After the thermally-induced dissociation of Fe ϩ i -B Ϫ s pairs, there could be increased concentration for the Fe ϩ i interstitials at the silicon side; thus, some of the Fe ϩ i interstitials could be gettered at the polysilicon layer by mass out-diffusion from the bulk silicon toward the polysilicon layer in response to the increased thermal agitation and the concentration gradient thus created. Nevertheless, the continual gettering for these ionic Fe ϩ i interstitials and to a certain extent for some neutral Fe i°i nterstitials, if present, at the polysilicon layer via diffusion was limited, as shown by the TXRF results for sample B in Fig.…”