Ellipsometer for texture Si solar cells T-Solar

From Woollam for textured Si solar cells

T-Solar, a special intensity optimized M-2000, addresses the measurement requirements on textures Si wafer surfaces.

SiN thickness of texture Si wafers
Rotating compensator ellipsometer
High intensity

The T-Solar ellipsometer combines the best photovoltaic measurement technology into a single system designed specifically for textured samples. Based on the established

M-2000 rotating compensator spectroscopic ellipsometer, the T-Solar measures hundreds of wavelength across the UV-Visible-NIR. To improve performance on rough, textured surfaces that significantly reduce reflected signal, the T-Solar combines a special high-intensity lamp source with our new Intensity-Optimizer*. The T-Solar is perfect for characterizing AR coatings on etched silicon surfaces. In addition, the T-Solar features an adjustable tilt-rotation-stage*, which is required to align the pyramid structures of alkaline-etched monocrystalline surfaces.

*patent pending

  • Spectral range 245 to 1000 nm (470 wavelengths)
  • Automated filter wheel to optimize signal on any sample
  • Custom sample stage with variable tilt (0-58°) and rotation (100° range) to allow optimized measurements of textured monocrystaline silicon "pyramid" sufaces
  • Detachable focusing probes
Textured substrate

The T-Solar system was specifically designed to measure AR coatings on textured substrates. Both the texturing and AR coating work to suppress reflection from the surface - making optical characterization challenging.

The texturing produced from alkaline etch of monocrystalline silicon has a regular pattern of pyramids that etch along specified directions of the silicon crystal. To measure this regular pattern of pyramids requires the special T-Solar measurement geometry. With the T-Solar, the sample stage can be tilted (and rotated) from the standard geometry to align the pyramids with the probe beam used for measurement.

Silicon solar cell
Monocrystalline silicon


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