Photoluminescence method for detecting trace levels of iron in ultrapure silicon

Abstract

A nondestructive technique is presented for the determination of trace levels of interstitial iron contamination in ultrapure silicon. This approach is based on the well-known ability of iron to undergo a reversible pairing reaction with boron near room temperature. A variety of float-zoned silicon samples with low concentrations of boron (∼1011 cm−3) were subjected to thermal annealing treatments to study changes in the apparent boron concentration as determined by the standard method of comparing the photoluminescence intensity of the boron bound exciton to that of the free exciton. Changes in the apparent boron concentration were attributed to the formation or dissociation of iron–boron pairs, allowing us to estimate the interstitial iron concentration in these samples. Remarkably, relatively mild thermal treatments can change the apparent boron concentration in some of these samples by up to a factor of ten.

Activation energies of the InSi‐Sii defect transitions obtained by carrier lifetime measurements

“…The A Si -Fe i defects were comprehensively investigated [31] and there are experiments, which indicate that a dissociation process indeed occurs [33,34]. In that case, the substitutional acceptor and the iron are fully separated.…”

Low‐Temperature Photoluminescence Investigation of Light‐Induced Degradation in Boron‐Doped CZ Silicon

“…Defect formation during illumination could cause a reduction in B TO (BE) intensity. Here, the defect formation leads to a reduction of the luminescent excitonic transitions, according to Broussell et al [ 10 ]…”

“…Defect formation during illumination could cause a reduction in B TO (BE) intensity. Here, the defect formation leads to a reduction of the luminescent excitonic transitions, according to Broussell et al [10] Figure 5b is shown to check for the existence of an additional excitonic transition in the TA or NP region. This peak should be analogous to the P line of the In Si -Si i defect.…”

“…We found this in Pelant et al [ 16 ] This is because stable measurement conditions and evaluation methods are of crucial importance, especially for the question of whether activation of the B Si –Si i defect leads to a reduction in the B TO (BE)/I TO (FE) intensity ratio. [ 10 ]…”

“…[ 9 ] Also, a reduction of the B TO (BE)/I TO (FE) ratio was observed due to the formation of iron–boron pairs. [ 10 ] I TO (FE) denotes the intrinsic luminescence peak caused by the transverse optical phonon‐assisted recombination of free excitons. Here, iron–boron complexes were observed after thermal annealing.…”