Development of evaluation system for solar cell by scanning with lens-focused white LED illumination

Using commercially available solar cell made of polycrystalline silicon as evaluation sample, we correctly observed the defects within the specified measurement range. The white light emitting diode (LED) was blinked at the specified frequency by the function generator, and the photovoltaic generated by its frequency was phase-detected by a lock-in amplifier. Not only the two types of defects intentionally created within the scanning area but also the polycrystalline silicon surface and the electrode could be distinguished clearly.