Abstract
Imaging techniques can be applied to multicrystalline silicon solar cells throughout the production process, which includes as early as when the bricks are cut from the cast ingot. Photoluminescence (PL) imaging of the band-to-band radiative recombination is used to characterize silicon quality and defects regions within the brick. PL images of the brick surfaces are compared to minority-carrierlifetimes measured by resonant-coupled photoconductive decay (RCPCD). Photoluminescence images on silicon bricks can be correlated to lifetime measured by photoconductive decay and could be used for high-resolution characterization of material before wafers are cut. The RCPCD technique has shown the longest lifetimes of any of the lifetime measurement techniques we have applied to the bricks.RCPCD benefits from the low-frequency and long-excitation wavelengths used. In addition, RCPCD is a transient technique that directly monitors the decay rate of photoconductivity and does not rely on models or calculations for lifetime. The measured lifetimes over brick surfaces have shown strong correlations to the PL image intensities; therefore, this correlation could then be used totransform the PL image into a high-resolution lifetime map.
Original language | American English |
---|---|
Number of pages | 7 |
State | Published - 2012 |
Event | 2012 IEEE Photovoltaic Specialists Conference - Austin, Texas Duration: 3 Jun 2012 → 8 Jun 2012 |
Conference
Conference | 2012 IEEE Photovoltaic Specialists Conference |
---|---|
City | Austin, Texas |
Period | 3/06/12 → 8/06/12 |
NREL Publication Number
- NREL/CP-5200-54115
Keywords
- charge-carrier lifetime
- imaging
- impurities
- infrared imaging
- photoconductivity
- photoluminescence
- photovoltaic cells
- silicon