Phosphorus gettering in multicrystalline silicon studied by neutron activation analysis

Macdonald, Daniel; Cuevas, Andrés; Kinomura, A.; Nakano, Yoshiro

doi:10.1109/pvsc.2002.1190514

Cited by 23 publications

(29 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Cu 3 Si clusters, or individual Cu atoms, may be stabilized either by the lattice strains of adjacent structural defects or other metal clusters. 21,70 Specifically, the chemical interactions between Cu and other metal species (of which mc-Si contains an abundance 24,26 ) are not well understood at the present time. The singular result of all these effects would likely be a somewhat lower effective segregation coefficient for mc-Si than that for singlecrystalline silicon.…”

Section: Al-gettering and Dissolution Of Cu Precipitatesmentioning

confidence: 98%

“…Not surprisingly, copper-rich particles have been observed at structural defects in poorly-performing regions of mc-Si solar cell material [21][22][23][24][25] , complementing neutron activation analysis (NAA) data reporting Cu concentrations in mc-Si as high as 10 13 cm -3 . 26 While Cu-rich clusters are undoubtedly not the only type of defect responsible for reducing the efficiencies of mc-Si solar cells, their known recombination activity and repeated observation in poorly-performing regions indicate they most certainly can be a contributing factor.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Analysis of copper-rich precipitates in silicon: Chemical state, gettering, and impact on multicrystalline silicon solar cell material

Buonassisi

Marcus

Istratov

et al. 2005

Journal of Applied Physics

View full text Add to dashboard Cite

In this study, synchrotron-based x-ray absorption microspectroscopy (µ-XAS) is applied to identifying the chemical states of copper-rich clusters within a variety of silicon materials, including as-grown cast multicrystalline silicon solar cell material with high oxygen concentration and other silicon materials with varying degrees of oxygen concentration and copper contamination pathways. In all samples, copper silicide (Cu 3 Si) is the only phase of copper identified. It is noted from thermodynamic considerations that unlike certain metal species, copper tends to form a silicide and not an oxidized compound because of the strong silicon-oxygen bonding energy; consequently the likelihood of encountering an oxidized copper particle in silicon is small, in agreement with experimental data. In light of these results, the effectiveness of aluminum gettering for the removal of copper from bulk silicon is quantified via x-ray fluorescence microscopy (µ-XRF), and a segregation coefficient is determined from experimental data to be at least (1-2)×10 3 . Additionally, µ-XAS data directly demonstrates that the segregation mechanism of Cu in Al is the higher solubility of Cu in the liquid phase. In light of these results, possible limitations for the complete removal of Cu from bulk mcSi are discussed.

show abstract

Section: Al-gettering and Dissolution Of Cu Precipitatesmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Analysis of copper-rich precipitates in silicon: Chemical state, gettering, and impact on multicrystalline silicon solar cell material

Buonassisi

Marcus

Istratov

et al. 2005

Journal of Applied Physics

View full text Add to dashboard Cite

show abstract

“…[1][2][3] These impurities can decrease the efficiencies of siliconbased devices in a variety of ways, including bulk recombination, 4,5 increased leakage current, [6][7][8] and direct shunting. 9,10 The groundbreaking study of Davis et al 11 specified threshold concentrations for individual metal species in Czochralski silicon (CZ-Si) photovoltaic devices, correlating the total metal content in a CZ-Si wafer to a quantified decrease in solar cell efficiency.…”

Section: Introductionmentioning

confidence: 99%

Chemical natures and distributions of metal impurities in multicrystalline silicon materials

Buonassisi

Istratov

Pickett

et al. 2006

Progress in Photovoltaics

171

106

View full text Add to dashboard Cite

We present a comprehensive summary of our observations of metal-rich particles in multicrystalline silicon (mc-Si) solar cell materials from multiple vendors, including directionally-solidified ingot-grown, sheet, and ribbon, as well as multicrystalline float zone materials contaminated during growth. In each material, the elemental nature, chemical states, and distributions of metal-rich particles are assessed by synchrotron-based analytical x-ray microprobe techniques. Certain universal physical principles appear to govern the behavior of metals in nearly all materials: (a) Two types of metal-rich particles can be observed (metal silicide nanoprecipitates and metal-rich inclusions up to tens of microns in size, frequently oxidized), (b) spatial distributions of individual elements strongly depend on their solubility and diffusivity, and (c) strong interactions exist between metals and certain types of structural defects. Differences in the distribution and elemental nature of metal contamination between different mc-Si materials can largely be explained by variations in crystal

show abstract

“…13 Other quantitative studies of the effect of phosphorous diffusion gettering have measured high chromium concentrations at near-surface regions, suggesting external gettering, [15][16][17] as well as a reduction of the total bulk chromium concentration. 18 For this study, two adjacent (sister) wafers were selected from a 12 kg laboratory-scale intentionally chromiumcontaminated mc-Si ingot. 11 These wafers were taken from 83% ingot height.…”

mentioning

confidence: 99%

“…13,[15][16][17][18] Lifetimes (Cr i , Dn ¼ 10 15 cm À3 ) and interstitial concentrations as measured by quasi-steady-state photoconductance (QSSPC) before and after gettering are shown in Fig. 3.…”

mentioning

confidence: 99%

Synchrotron-based analysis of chromium distributions in multicrystalline silicon for solar cells

Jensen

Hofstetter

Morishige

et al. 2015

Applied Physics Letters

View full text Add to dashboard Cite

Chromium (Cr) can degrade silicon wafer-based solar cell efficiencies at concentrations as low as 1010 cm−3. In this contribution, we employ synchrotron-based X-ray fluorescence microscopy to study chromium distributions in multicrystalline silicon in as-grown material and after phosphorous diffusion. We complement quantified precipitate size and spatial distribution with interstitial Cr concentration and minority carrier lifetime measurements to provide insight into chromium gettering kinetics and offer suggestions for minimizing the device impacts of chromium. We observe that Cr-rich precipitates in as-grown material are generally smaller than iron-rich precipitates and that Cri point defects account for only one-half of the total Cr in the as-grown material. This observation is consistent with previous hypotheses that Cr transport and CrSi2 growth are more strongly diffusion-limited during ingot cooling. We apply two phosphorous diffusion gettering profiles that both increase minority carrier lifetime by two orders of magnitude and reduce [Cri] by three orders of magnitude to ≈1010 cm−3. Some Cr-rich precipitates persist after both processes, and locally high [Cri] after the high-temperature process indicates that further optimization of the chromium gettering profile is possible.

show abstract

Phosphorus gettering in multicrystalline silicon studied by neutron activation analysis

Cited by 23 publications

References 16 publications

Analysis of copper-rich precipitates in silicon: Chemical state, gettering, and impact on multicrystalline silicon solar cell material

Analysis of copper-rich precipitates in silicon: Chemical state, gettering, and impact on multicrystalline silicon solar cell material

Chemical natures and distributions of metal impurities in multicrystalline silicon materials

Synchrotron-based analysis of chromium distributions in multicrystalline silicon for solar cells

Contact Info

Product

Resources

About