Quantitative copper measurement in oxidized p-type silicon wafers using microwave photoconductivity decay

Väinölä, Hele; Saarnilehto, Eero; Yli-Koski, Marko; Haarahiltunen, Antti; Sinkkonen, J.; Berenyi, G.; Pavelka, T.

doi:10.1063/1.1999008

Cited by 27 publications

(27 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…the lifetime/diffusion length variation before and after light soaking) has been correlated to quantitative measurements of the interstitial Cu concentrations involved in the degradation process. 23,24 After transforming the measured diffusion lengths into the corresponding lifetimes and inserting the obtained lifetime values into the empirical formula proposed in Ref. 24, we find an average Cu concentration of ∼7 × 10 13 cm 3 in the reference samples with no emitter, which approximately corresponds to the Cu contamination levels reported by several authors in as-cut solar-grade wafers.…”

Section: Resultsmentioning

confidence: 54%

“…23,24 After transforming the measured diffusion lengths into the corresponding lifetimes and inserting the obtained lifetime values into the empirical formula proposed in Ref. 24, we find an average Cu concentration of ∼7 × 10 13 cm 3 in the reference samples with no emitter, which approximately corresponds to the Cu contamination levels reported by several authors in as-cut solar-grade wafers. 1,12,25 In Group A, the residual Cu concentration after gettering is estimated to be ∼3.8 ×10 13 cm 3 (i.e.…”

Section: Resultsmentioning

confidence: 54%

See 1 more Smart Citation

Cu gettering by phosphorus-doped emitters in p-type silicon: Effect on light-induced degradation

et al. 2018

View full text Add to dashboard Cite

The presence of copper (Cu) contamination is known to cause relevant light-induced degradation (Cu-LID) effects in p-type silicon. Due to its high diffusivity, Cu is generally regarded as a relatively benign impurity, which can be readily relocated during device fabrication from the wafer bulk, i.e. the region affected by Cu-LID, to the surface phosphorus-doped emitter. This contribution examines in detail the impact of gettering by industrially relevant phosphorus layers on the strength of Cu-LID effects. We find that phosphorus gettering does not always prevent the occurrence of Cu-LID. Specifically, air-cooling after an isothermal anneal at 800°C results in only weak impurity segregation to the phosphorus-doped layer, which turns out to be insufficient for effectively mitigating Cu-LID effects. Furthermore, we show that the gettering efficiency can be enhanced through the addition of a slow cooling ramp (-4°C/min) between 800°C and 600°C, resulting in the nearly complete disappearance of Cu-LID effects.

show abstract

Section: Resultsmentioning

confidence: 54%

Section: Resultsmentioning

confidence: 54%

Cu gettering by phosphorus-doped emitters in p-type silicon: Effect on light-induced degradation

et al. 2018

View full text Add to dashboard Cite

show abstract

“…In Cz samples with intentionally grown oxygen precipitates, Cu-LID has been shown to exhibit degradation behavior that can be interpreted to be characteristic of heterogeneous nucleation. 19 This means that the degradation rate of Cu-LID increased and final lifetime decreased considerably when the density of nucleation sites provided by the oxide precipitates was increased. On the other hand, Cu-LID derived from homogeneous precipitation was speculated to occur in wafers that did not undergo the intentional nucleation site creation stage.…”

mentioning

confidence: 99%

“…11,12 In p-type Si, provided that the Cu contamination level is below the doping level, excess carrier injection (through, e.g., illumination) is necessary to activate lifetime degradation. 11,[13][14][15][16][17][18][19][20] For these reasons, Cu-related lightinduced degradation (Cu-LID) is only observed in p-type Si. Owing to the fundamental difference in defect activation between n-and p-type Si, especially early contributions 11,13 attributed Cu-LID in p-type Si to a different defect than precipitates, and ambiguity has existed ever since.…”

Section: Introductionmentioning

confidence: 99%

Modeling of light-induced degradation due to Cu precipitation in p-type silicon. I. General theory of precipitation under carrier injection

Vahlman

Haarahiltunen

Kwapil

et al. 2017

Journal of Applied Physics

Self Cite

View full text Add to dashboard Cite

Copper contamination causes minority carrier lifetime degradation in p-type silicon bulk under illumination, leading to considerable efficiency losses in affected solar cells. Although the existence of this phenomenon has been known for almost two decades, ambiguity prevails about the underlying defect mechanism. In Paper I of this two-part contribution, we propose the first comprehensive mathematical model for Cu-related light-induced degradation in p-type silicon (Cu-LID). The model is based on the precipitation of interstitial Cu ions, which is assumed to be kinetically limited by electrostatic repulsion from the growing Cu precipitates. Hence, growth and dissolution rates of individual Cu precipitates are derived from the drift-diffusion equation of interstitial Cu and used in a kinetic precipitation model that is based on chemical rate equations. The kinetic model is interlinked to a Schottky junction model of metallic precipitates in silicon, enabling accurate calculation of the injection-dependent electric field enclosing the precipitates, as well as the precipitate-limited minority carrier lifetime. It is found that a transition from darkness to illuminated conditions can cause an increase in the kinetics of precipitation by five orders of magnitude. Since our approach enables a direct connection between the time evolution of precipitate size-density distribution and minority carrier lifetime degradation under illumination, a procedure for calculating the Cu-LID-related lifetime as a function of illumination time is included at the end of this article. The model verification with experiments is carried out in Paper II of this contribution along with a discussion of the kinetic and energetic aspects of Cu-LID. Published by AIP Publishing.

show abstract

“…Intrinsic optical absorption in single crystal germanium (Ge) and Si was studied 4 at the temperatures 77 and 300K, the threshold for direct transition was found to be at 2.5 eV and that for indirect transitions were at 1.06 eV and 1.16 eV at 300 and 77K, respectively. Microwave Photoconductive decay (µ-PCD) was used 5 to find out the copper (Cu) contamination in p-type Si and it was found that the method was capable of measuring Cu concentrations down to 10 10 /cm 3 . The optical parameters and the thickness of Si: H thin films were determined 6 from transmission spectrum in the range of 400-2500 nm using the envelope method and detailed analysis was carried out to obtain the optical band gap (E g ) using Tauc's method and the estimated values were 1.99 eV, 2.01eV and 1.75 eV.…”

Section: Introductionmentioning

confidence: 99%

Electrical Optical and Structural Properties of p-type Silicon

Sharmin

Choudhury

Begum

2015

Dhaka Univ. J. Sci.

View full text Add to dashboard Cite

Electrical, optical and structural properties of p-type single crystal silicon were investigated in this work. Electrical conductivity of p-type silicon was measured in the temperature ranges 190 -300 K. The acceptor ionization energy ( E A ) was between 0.047 -0.051 eV. Photoconductivity of the material was investigated by varying sample current, light intensity and temperature at a constant chopping frequency of 45.60 Hz. Absorption co-efficient ( ) of the material was calculated from optical transmittance and reflectance measurements at room temperature (300 K) in the wavelength range of 300 -2500 nm. The direct optical band gap energy was found between 2.10 -2.20 eV and the indirect optical band gap energy was found between 0.95 -1.0 eV. The lattice parameter (a) was found to be 5.419Å from X-ray diffraction method (XRD).

show abstract

Quantitative copper measurement in oxidized p-type silicon wafers using microwave photoconductivity decay

Abstract: Iron detection in polished and epitaxial silicon wafers using generation lifetime measurements

Cited by 27 publications

References 15 publications

Cu gettering by phosphorus-doped emitters in p-type silicon: Effect on light-induced degradation

Cu gettering by phosphorus-doped emitters in p-type silicon: Effect on light-induced degradation

Modeling of light-induced degradation due to Cu precipitation in p-type silicon. I. General theory of precipitation under carrier injection

Electrical Optical and Structural Properties of p-type Silicon

Contact Info

Product

Resources

About