EPR of defects in silicon-on-insulator structures formed by ion implantation. I. O⁺implantation

The location and annealing of paramagnetic oxygen vacancies (E1' centres) in silicon implanted with high doses of oxygen

“…The absence of E; centres in the outer shell of the precipitates also explains the change produced by etching the sample. The silicon removed first contains the smallest precipitates; these, having a high surface/volume ratio, may have a significant proportion of all the P, centres at the oxide precipitate/silicon interface but a small proportion of the E; centres and hence the etch would initially decrease the P, centre population more than that of the E: centres, as we observed [ 3 ] .…”

“…The two features A and C are common to all the samples except one: feature C is undetectable for the lowest dose sample. The defects (amorphous silicon centres in bulk silicon and P, centres at oxide precipitate/silicon interfaces; P, centres are silicon dangling bonds at Si/SiO, interfaces) which are responsible for feature A have been discussed elsewhere [3]. Here we are concerned only with the feature C. It is slightly asymmetric, isotropic, has a zero crossing g value, go> (corresponding to the point where the signal crosses the base line) of 2.0003 f 0.0004, saturates easily with increasing microwave power and, for a dose of 1.4 x has a peak-to-peak linewidth of 0.30 & 0.03 mT.…”

“…We found [4] that, for samples implanted with 1.4 x 10ld Oc cm-' at 250,450 or 600'C, the E; centres begin to anneal for T 2 450 "C. We now observe the same behaviour in a sample implanted with 1.2 x IO'* O+ cm-' at 62OOC. However, for a dose of 1.8 x lo1* O+ cm-, the annealing begins at T 2 350'C [3]. One question that arises is whether or not this annealing is irreversible.…”

“…centres. When a sample implanted with 1.8 x 1OI8 0 was immersed in a KOH etch (for silicon) we found [3] that initially there was a decrease in the population of the amorphous silicon centres and P, centres but no change in that of E; centres. This is certainly consistent with our original suggestion [3] that the latter are in the buried oxide layer.…”

“…Our experiments were in fact begun with the aim of determining the location of the E: centres. Some earlier measurements [3] suggested that the E; centres are in the buried layer but this conclusion appeared to be contradicted by later experiments which showed that there certainly are E; centres in the precipitates [4]. We started therefore with the aim of determining whether these centres are in both regions or only in one.…”