Abstract
This work shows an alternative surface cleaning method for c-Si wafers to replace the standard chemical procedures as RCA or HNO 3 which involve hazardous chemicals or unstable processes. The method consists in a high-temperature oxidation treatment (HTO) performed in a classical tube furnace that incorporates organic and metal particles present on the c-Si surfaces in the growing SiO 2 layer. The result is as a reliable pre-treatment method for obtaining less defective c-Si surfaces ready for solar cell fabrication after SiO 2 removal. To test the surface passivation quality obtained with our alternative cleaning method, we grow amorphous silicon (a-Si:H) layers by plasma enhanced chemical vapor deposition on both sides of the c-Si wafer and systematically compare the effective carrier lifetime (τ eff ) and implied V OC (iV oc ) to the wafer treated with the standard cleaning in our laboratory. We optimize HTO treatment time reaching τ eff of ∼6 ms and iV oc of 721 mV for the best sample. We ascribe the improved passivation quality using HTO to two concurrent factors. Firstly, the encapsulation of defects into SiO 2 layer that is then etched prior a-Si:H deposition and secondly, to modification of the pyramids’ morphology that facilitates the surface passivation. SEM pictures and reflection measurements support the latter hypothesis.
Original language | English |
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Pages (from-to) | 67-70 |
Number of pages | 4 |
Journal | Materials Science in Semiconductor Processing |
Volume | 97 |
DOIs | |
Publication status | Published - 2019 |
Bibliographical note
Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Keywords
- Amorphous silicon passivation
- Defect encapsulation
- Silicon heterojunction solar cells
- Thermal oxidation