Vanadium in silicon: Lattice positions and electronic properties

Abstract

The electronic properties of vanadium in silicon have been studied using deep level transient spectroscopy (DLTS), high resolution Laplace DLTS, capacitance voltage measurements and secondary ion mass spectroscopy (SIMS). Vanadium was implanted into float zone (FZ) grown n-type and FZ and Czochralski (Cz) grown p-type Si and implantation damage was removed through annealing between 700 and 900 °C. DLTS measurements were carried out to determine the electronic characteristics of vanadium-related defects in silicon. It is argued that the dominant electrically active defect is related to interstitial vanadium (Vi) atoms. The distribution of implanted vanadium is seen to differ between Czochralski and FZ silicon, with redistribution of vanadium atoms occurring significantly faster in Cz-Si. We suggest that in FZ-Si the Vi atoms interact with implantation induced vacancies and move to the substitutional site where they are much less mobile. At the peak concentration of vanadium, determined by SIMS to be ∼1015 cm−3 in FZ-Si, the electrically active fraction is significantly lower (∼1013 cm–3). As we see no evidence of precipitation occurring in the region close to the implant peak, it is concluded that a large portion of V atoms should be located at the substitutional site. Despite the ab-initio modeling predictions of substitutional vanadium, Vs, introducing a shallow acceptor level in the silicon band gap, no electrical activity associated with the Vs fraction has been observed in this work in spite of its concentration being at a measurable level. As such, our results indicate that substitutional vanadium is electrically inactive in silicon.

Recombination via transition metals in solar silicon: The significance of hydrogen–metal reactions and lattice sites of metal atoms

“…To date, we have shown this effect to occur for two of the three transition metals discussed so far in this paper, titanium and vanadium, when excess vacancies are introduced by implantation . For both of these metals, displacement to the substitutional site has been observed in float zone silicon implanted with metal ions after annealing at high temperature.…”

“…At this site, these atoms have a significantly lower diffusivity, accounting for the discrepancy in redistribution between the two materials. It was also concluded that as no further evidence of electrical activity was observed either in capacitance‐voltage measurements or in DLTS that the TM atoms are electrically inactive at this site .…”

Analysis of the dark current distribution of complementary metal-oxide-semiconductor image sensors in the presence of metal contaminants

“…Indeed, in molybdenum-contaminated samples the dark current distribution peaks at a higher current and shows larger spread than the intrinsic distribution. This result is expected since molybdenum was previously shown to have relevant impact on junction leakage [15][16][17]. This fact is mainly due to the low molybdenum diffusivity [18].…”

(Invited) Deep-Level Analysis of Passivation of Transition Metal Impurities in Silicon

“…One large peak is seen in the DLTS spectra at ~260 K and is related to hole emission from the second donor level of interstitial vanadium (V i +/++ ) (11), which is located at 0.34 eV above the valence band edge. A small additional peak at ~ 50 K is also observed, and is likely due to the FeB complex, introduced by contamination during processing of the samples.…”

“…While the formation of complexes of transition metals and hydrogen has been shown to be effective for reducing the electrical activity of transition metals in silicon, it has been found recently that slow diffusing TMs can be made inactive by displacing them to the substitutional site (10,11). According to the results of ab-initio calculations the formation energies of interstitial TM atoms in silicon is smaller compared to those for TMs at substitutional site, however, if lattice vacancies are available the interstitial TMs tend to interact with the vacancies and occupy the lattice site with a significant gain in total energy of the system (10,(12)(13)(14).…”