Carrier Lifetime Stability of Boron-Doped Czochralski-Grown Silicon Materials for Years After Regeneration in an Industrial Belt Furnace

• Published in: IEEE journal of photovoltaics 2022-01, Vol.12 (1), p.198-203
• Main Authors: Helmich, Lailah, Walter, Dominic, Pernau, Thomas, Schmidt, Jan
• Format: Article
• Language: English
• Subjects: Annealing; Belt conveyors; Belts; Boron; Boron–oxygen (BO) defect; Carrier lifetime; Czochralski-grown silicon (Cz-Si); Degradation; Furnaces; light-induced degradation (LID); Lighting; long-term stability; Regeneration; Silicon; Silicon wafers; Stability; Sun; Temperature measurement
• ISSN: 2156-3381; 2156-3403
• DOI: 10.1109/JPHOTOV.2021.3116019

We examine the long-term stability of the carrier lifetime in boron-doped Czochralski-grown silicon materials with different boron and oxygen concentrations, which were regenerated in an industrial belt furnace. After firing and subsequent regeneration in an industrial conveyor-belt furnace, the silicon samples are exposed to long-term illumination at an intensity of 0.1 suns and a sample temperature of about 30 °C for more than two years. After regeneration, we observe a minor re-degradation (30-72% reduced compared to the degradation observed without regeneration step). We attribute this re-degradation to a non-completed regeneration within the belt furnace due to the short regeneration period. Our results show that the industrial process consisting of firing with subsequent regeneration in the same unit is very effective for industrially relevant silicon materials. Typical industrial silicon wafers with a resistivity of (1.75 ± 0.03) Ωcm and an interstitial oxygen concentration of (6.9 ± 0.3) × 10 17 cm -3 show lifetimes larger than 2 ms after regeneration and two years of light exposure.