Characterization of near-surface electrical properties of multi-crystalline silicon wafers

This experiment is concerned with photoconductive decay (PCD) measurements devised specifically for the purpose of characterization of the near-surface region of semiconductor substrates. Specifically, the method is utilized to evaluate the effects of crystallographic orientation, grain boundaries, and surface texturing on the near-surface electrical properties of multi-crystalline silicon (mc-Si) wafers used for solar cell applications. The PCD method is also explored for the purposes of monitoring processes used in the manufacture of mc-Si solar cells. The effect of saw damage and damage removal by wet etching on the near-surface lifetime of minority carriers and carrier mobility in mc-Si wafers is quantitatively determined. The results obtained demonstrate a direct correlation between condition of the mc-Si surface and the electrical parameters measured. It is postulated that the PCD method using temporary contact can be effectively used to monitor the condition of mc-Si surfaces during solar cell manufacturing.