A fully automated system for local spectral characterization of photovoltaic structures

The system presented in this work shows a good repeatability (0.5%) and high accuracy (6.3%) in the computer controlled spectral characterization of photovoltaic devices by the determination of internal quantum efficiency over an extended wavelength range. Biasing conditions (for both light and voltage) are fully controlled by computer as well. A corresponding I-V curve can be obtained in the same location without moving the sample on a different set-up. Scanning images (maps) of internal quantum efficiency (IQE) and of external quantum efficiency (QE) can be obtained with a spatial resolution better than 10 microns. Parameters extracted from I-V curves can be mapped with the same spatial resolution. Because IQE curves and I-V curves are obtained in the same location and using same optics, a full characterization of the photovoltaic device under test is possible in a single run. By providing the high accuracy and extended versatility, this system will have wide-range of application in photovoltaics both research and production.