Effect of boron on formation of interstitial‐related luminescence centres in ion implanted silicon

Abstract

The presence of boron in silicon has been shown to have a deleterious effect on the luminescence of interstitial‐related centres, particularly the W‐centre which is often observed after ion implantation and a low temperature anneal. Competition between silicon‐interstitial and boron‐interstitial centre formation is considered to be a possible mechanism underlying this dramatic reduction. Previous work on silicon implantation of boron‐doped substrates is extended to examine the effect of B implantation itself on W‐centre formation. W centres formed via the implantation of B and a low temperature anneal and via a Si implant over an activated B‐implant profile followed by low temperature anneal are compared. These studies contrast the effects of boron and silicon implantation and examine the effect of overlapping implantation profiles. Studying the effect of boron on optical centre formation provides insight into defect interactions in silicon and new data for theoretical modelling.

Dopant effects on the photoluminescence of interstitial-related centers in ion implanted silicon

“…As discussed in our previous work, both implanted and bulk B has a detrimental effect on the W line intensity. 9,10 We observe the opposite behaviour for P consistent with a study by Giri. 5 The relative intensities for samples (i):(ii):(iii) is approximately 9:5:1 at this measurement and anneal temperature.…”

“…A single B implant to a fluence of 1 Â 10 15 cm À2 is not expected to result in the W line. 10 Here, we observe the W line because of the additional interstitials injected beyond the extent of the B profile by a subsequent Si implant. Strong W, X, and Y lines can, therefore, be observed simultaneously.…”

“…The B implants result in a significant reduction of the W line and other interstitial-related PL lines with the B imp case having a more detrimental effect. 10 The anneal temperature at which the W-line is maximum is found to be dopant dependent. For B and Ga, it is 225 C. P shifts the optimum temperature up by 50-100 C.…”

“…Instead, the W line arises from the channeling tail of the profile. 10 Nevertheless, under all processing conditions, the presence of B was found to be detrimental to the self-interstitial-related PL yield. This has been suggested to be a result of the prevention of W center formation or the creation of alternative non-radiative recombination pathways.…”

“…7,8 Recently, we showed that the interaction between B and self-interstitials leads to a reduction in the PL intensity of interstitial-related centers and identified a B concentration of 3:2 Â 10 18 cm À3 above which no W line is observed. 9,10 This was ascribed to either the prevention of the formation of these centers or the preferential non-radiative recombination at B-interstitial clusters (BICs). The tightly bound selfinterstitials in these BICs persist to higher anneal temperatures where the formation of RLDs (and the so called R line luminescence from these defects) may also be inhibited.…”