The Properties of Iron in Silicon

Abstract

The properties of iron in n-type and p-type silicon were studied by means of DLTS, carrier lifetime measurements, and infrared absorption spectroscopy. Only one donor level was observed, situated at Ev § 0.43 eV and correlated to iron on an interstitial site. In p-St: B iron-boron pairs were formed at room temperature. Their activation energy was determined to be Ev -6 0.10 eV. The reaction proceeded in two phases. In the second phase a thermal equilibrium between iron and iron-boron pairs was found which could be shifted by annealing and illuminating the specimen, respectively. In aluminum-doped silicon crystals two levels were observed after iron diffusion correlated to iron-aluminum pairs. Their activation energies were determined to be Ev -60.21 and 0.13 eV. It is assumed that iron-boron pairs form also two levels, a donor and an acceptor. The acceptor must be situated in the upper half of the silicon bandgap. Reaction mechanisms are discussed.

Recombination at Lomer Dislocations in Multicrystalline Silicon for Solar Cells

“…In boron-doped Si material, Fe i tends to pair with B, leading to iron-boron pairs (FeB), which are less recombination active than Fe i [16], [21]. Fe i and FeB are attributed to defect levels with energies of 0.4 eV [22], [23] above the valence band level E V , and 0.26 eV below the conduction band level E C [24]- [26], respectively.…”

An investigation of the effects of iron in p/sup +/n silicon diodes for simulated plasma source ion implantation studies

“…The effects of iron in silicon have been examined previously [12]- [15]. With various trapping levels reported throughout the band gap, we expected to see the leakage-current density increase with increasing iron dose.…”

Eliminating Light-Induced Degradation in Commercial p-Type Czochralski Silicon Solar Cells

“…The benefit of using gallium-doped wafers is that they are free of any B-O related LID effects. However, like boron-doped wafers, they are susceptible to the formation of acceptor-iron pairs [53,54]. A weakness of gallium-doped ingots is the substantially lower segregation coefficient for gallium (8 × 10 −3 ) than that for boron (0.8) [55,56].…”