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Institut Silizium-Photovoltaik

Optimisation of saw damage removal to reduce interface recombination losses

Saw Damage Etching (SDE) decreases step-wise the recombination losses. Too long SDE, however, increases surface defects and recombination losses due to inhomogeneous etching and initial formation of random pyramids. The etching time influences the saw etching dept, as well as the emerging Si surface morphology. Therefore, the SDE process has to be carefully optimised with respect to the kind of Si substrate manufacturing.

sde trans

Fig. 1 b Change of time decay of SPV pulses on as cut p-type CZ Si during saw damage etching (SDE) in KOH solution 

Fig. 2b  Dit(E) after short (curves 1, 3)  and completed (curves 2, 4) SDE and subsequent cleaning in RCA + HF (curves 1, 2) and additional smoothing in H2SO4:H2O2 + HF (curves 3, 4).


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