Minority-carrier lifetime and defect content of n-type silicon grown by the noncontact crucible method

Maulid Kivambe, Douglas M. Powell, Sergio Castellanos, Mallory Ann Jensen, Ashley E. Morishige, Kazuo Nakajima, Kohei Morishita, Ryota Murai, Tonio Buonassisi

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

We evaluate minority-carrier lifetime and defect content of n-type photovoltaic silicon grown by the noncontact crucible method (NOC-Si). Although bulk impurity concentrations are measured by inductively coupled plasma mass spectroscopy to be less than one part per million, homogeneously throughout the as-grown material we observe lifetimes in the ~150 μs range, well below the theoretical entitlement of single-crystalline silicon. These observations suggest the presence of homogeneously distributed recombination-active point defects. We compare an industry-standard gettering profile to an extended gettering profile tailored for chromium extraction, to elucidate potential gains and limitations of impurity gettering. Near the ingot top, gettering improves lifetimes to 750 and >1800 μs for standard and extended profiles, respectively. Relatively lower gettered lifetimes are observed in wafers extracted from the ingot middle and bottom. In these regions, concentric-swirl patterns of low lifetime are revealed after gettering. We hypothesize that gettering removes a large fraction of fast-diffusing recombination-active impurities, while swirl microdefect regions reminiscent of Czochralski silicon can locally limit gettering efficiency and lifetime. Apart from these swirl microdefects, a low dislocation density of <103 cm-2 is observed. The millisecond lifetimes and low dislocation density suggest that, by applying appropriate bulk microdefect and impurity control during growth and/or gettering, n-type NOC-Si can readily support solar cells with efficiencies >23%.

Original languageEnglish
Pages (from-to)31-36
Number of pages6
JournalJournal of Crystal Growth
Volume407
DOIs
Publication statusPublished - 1 Nov 2014
Externally publishedYes

Fingerprint

Carrier lifetime
Crucibles
Silicon
crucibles
carrier lifetime
minority carriers
Impurities
Ingots
life (durability)
Defects
defects
silicon
ingots
impurities
Inductively coupled plasma
Chromium
Point defects
profiles
Spectroscopy
Crystalline materials

Keywords

  • A1. Defects
  • A1. Impurities
  • A2. Top-seeded solution growth
  • B2. Semiconducting silicon
  • B3. Solar cells

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Materials Chemistry
  • Inorganic Chemistry

Cite this

Kivambe, M., Powell, D. M., Castellanos, S., Ann Jensen, M., Morishige, A. E., Nakajima, K., ... Buonassisi, T. (2014). Minority-carrier lifetime and defect content of n-type silicon grown by the noncontact crucible method. Journal of Crystal Growth, 407, 31-36. https://doi.org/10.1016/j.jcrysgro.2014.08.021

Minority-carrier lifetime and defect content of n-type silicon grown by the noncontact crucible method. / Kivambe, Maulid; Powell, Douglas M.; Castellanos, Sergio; Ann Jensen, Mallory; Morishige, Ashley E.; Nakajima, Kazuo; Morishita, Kohei; Murai, Ryota; Buonassisi, Tonio.

In: Journal of Crystal Growth, Vol. 407, 01.11.2014, p. 31-36.

Research output: Contribution to journalArticle

Kivambe, M, Powell, DM, Castellanos, S, Ann Jensen, M, Morishige, AE, Nakajima, K, Morishita, K, Murai, R & Buonassisi, T 2014, 'Minority-carrier lifetime and defect content of n-type silicon grown by the noncontact crucible method', Journal of Crystal Growth, vol. 407, pp. 31-36. https://doi.org/10.1016/j.jcrysgro.2014.08.021
Kivambe, Maulid ; Powell, Douglas M. ; Castellanos, Sergio ; Ann Jensen, Mallory ; Morishige, Ashley E. ; Nakajima, Kazuo ; Morishita, Kohei ; Murai, Ryota ; Buonassisi, Tonio. / Minority-carrier lifetime and defect content of n-type silicon grown by the noncontact crucible method. In: Journal of Crystal Growth. 2014 ; Vol. 407. pp. 31-36.
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