Application of illuminated lock-in thermography to industrial silicon solar cells

Illuminated lock-in thermography (ILIT) was introduced for spatially resolved measurement of the local power dissipation in a solar cell. For this paper, industrial silicon solar cells were processed and ILIT images taken after each process step, starting with the emitter diffusion. Non ideal processing during the wafer texturization, the contact firing and the laser edge isolation was intentionally applied in order to show the influence of the various dissipation channels in ILIT images. As a result, it is shown that edge shunts due to low laser edge isolation quality are only visible in ILIT MPP images if the global Rp is lower than approximately 1 k ohm cm2.