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Approach to Clarify the Cause of Handling Defects in Silicon Heterojunction Cell Production through the Interplay of Different Imaging Techniques

: Fischer, A.; Vulcanean, I.V.; Moldovan, A.; Rentsch, J.

Fulltext urn:nbn:de:0011-n-5655019 (625 KByte PDF)
MD5 Fingerprint: 3f35e309314c5597f9d2eb5064bb821b
Created on: 26.11.2019

36th European Photovoltaic Solar Energy Conference and Exhibition, EU PVSEC 2019 : Proceedings of the international conference held in Marseille, France, 09-13 September 2019
Marseille, 2019
ISBN: 3-936338-60-4
European Photovoltaic Solar Energy Conference and Exhibition (EU PVSEC) <36, 2019, Marseille>
Conference Paper, Electronic Publication
Fraunhofer ISE ()
Photovoltaik; Silicium-Photovoltaik; Oberflächen: Konditionierung; Passivierung; Lichteinfang; heterojunction; a-Si; automation; induced defects

Within this paper, a systematic approach will be presented to clarify the origin of locally reduced carrier lifetime caused by conveyor belts and vacuum grippers used for automated wafer handling. The most sensitive handling step in silicon heterojunction production is between wet-chemical cleaning and amorphous-Silicon (a-Si) layer deposition by plasma enhanced chemical vapor deposition (PECVD). In this state the wafer surface should be clean, defect-free and H-terminated what should not be altered by the automation. The handling takes place at room temperature before first side a-Si layer deposition and at elevated temperatures, resulting from residual heat of the previous deposition, before second side deposition. This paper focuses on the interplay of different imaging techniques to identify the cause of conveyor belt and gripper induced locally reduced carrier lifetime. Photoluminescence imaging (PL) is used to display the electrical properties of the passivated silicon surface in a spatially resolved manner. In addition micro photoluminescence imaging (µ-PL) images were taken to examine details in a small area. These images are applied to navigate to the handling system induced defects on the wafer surface by image navigation in a scanning electron microscope (SEM). At the end of the investigation chain, electron dispersive X-ray spectroscopy (EDX) is used to analyze the found irregularities concerning their chemical composition.