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2019
Conference Paper
Titel
Impact of Vacuum Grippers Utilized for Automated Wafer Handling Prior a-Si Passivation for Silicon Heterojunction Solar Cells
Abstract
In this work the impact of grippers used in current photovoltaic mass production prior amorphous Silicon (a-Si) passivation for silicon heterojunction (SHJ) solar cells was investigated. Therefore large area Czochralski grown silicon (Cz-Si) wafers were handled by different types of vacuum grippers after cleaning and prior passivation. The study focuses on two aspects. The first focus is on the impact towards a-Si passivation caused by the interaction between gripper and wafer surface, measured by lifetime calibrated photoluminescence (PL) spectroscopy. The second focus lies on the optical and chemical analysis of the gripper affected wafer surface by scanning electron microscopy (SEM) and electron dispersive x-ray spectroscopy (EDX). It is demonstrated that particles can be considered as the main reason for gripper induced passivation defects. For passivation of wafers handled with cleaned vacuum based grippers with a surface out of a low contamination potential material it is shown, that the lifetime remains unchanged within a range of ± 0.2 ms on a level of 3 ms in comparison to a unhandled wafer.