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).

Publikationen

  • Angermann, H.; Laades, A.; Kegel, J.; Klimm, C.; Stegemann, B.: Improvement of silicon solar cell substrates by wet-chemical oxidation studied by surface photovoltage measurements. Solid State Phenomena 219 (2015), p. 291-296
  • Stegemann, B.; Kegel, J.; Mews, M.; Conrad, E.; Korte, L.; Stürzebecher, U.; Angermann, H.: Evolution of the charge carrier lifetime characteristics in crystalline silicon wafers during processing of heterojunction solar cells. Energy Procedia 55 (2014), p. 219–228
  • Kegel, J.; Angermann, H.; Stürzebecher, U.; Conrad, E.; Korte, L.; Stegemann, B.: IPA-free textured a-Si:H/C-Si heterojunction solar cells exceeding 20 % efficiency. In: Proc 28th European Photovoltaic Solar Energy Conference (2013), 2013.
  • Angermann, H.; Laades, A.; Stürzebecher, U.; Conrad, E.; Klimm, C.; Schulze, T.F.; Jacob, K.; Lawerenz, A.; Korte, L.: Wet-chemical preparation of textured silicon solar cell substrates: Surface conditioning and electronic interface properties. Solid State Phenomena 187 (2012), p. 349-352