Synchrotron-based investigation of transition-metal getterability in n-type multicrystalline silicon
Abstract
Solar cells based on n-type multicrystalline silicon (mc-Si) wafers are a promising path to reduce the cost per kWh of photovoltaics; however, the full potential of the material and how to optimally process it are still unknown. Process optimization requires knowledge of the response of the metal-silicide precipitate distribution to processing, which has yet to be directly measured and quantified. To supply this missing piece, we use synchrotron-based micro-X-ray fluorescence (μ-XRF) to quantitatively map >250 metal-rich particles in n-type mc-Si wafers before and after phosphorus diffusion gettering (PDG). We find that 820 °C PDG is sufficient to remove precipitates of fast-diffusing impurities and that 920 °C PDG can eliminate precipitated Fe to below the detection limit of μ-XRF. Thus, the evolution of precipitated metal impurities during PDG is observed to be similar for n- and p-type mc-Si, an observation consistent with calculations of the driving forces for precipitate dissolution and segregation gettering. Measurements show that minority-carrier lifetime increases with increasing precipitate dissolution from 820 °C to 880 °C PDG, and that the lifetime after PDG at 920 °C is between the lifetimes achieved after 820 °C and 880 °C PDG.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- May 16, 2016
- Source ID
- 10.1063/1.4950765
Entities
People
- Ashley E Morishige
- Barry Lai
- Chenlei Wang
- David P. Fenning
- Jasmin Hofstetter
- Mallory A. Jensen
- Patricia X. T. Yen
- Tonio Buonassisi
Organizations
- Argonne National Laboratory
- Massachusetts Institute of Technology
- National Science Foundation
- United States Department of Defense
- United States Department of Energy
- University of California