Dresden 2014 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 71: Energy materials: Silicon-based photovoltaics

HL 71.6: Vortrag

Mittwoch, 2. April 2014, 16:15–16:30, POT 151

Iron-related traps in near-junction volume of crystalline silicon solar cells — •Teimuraz Mchedlidze and Jörg Weber — Technische Universität Dresden, 01062 Dresden, Germany

Deep traps of majority carriers were detected recently in the near-to-junction volume (NJV) of fully processed crystalline solar cells [1]. The traps were detected using mesa-structured n+p-junctions prepared on the processed Si solar cells by deep level transient spectroscopy (DLTS). In this report we present an investigation of the trap formation at various stages of the standard solar cell fabrication process. The samples fabricated from the Czochralski-grown crystals with various initial iron contents were investigated. Total iron content in the samples was determined by DLTS in the as-grown samples subjected to high-temperature annealing followed by fast quenching. The NJV trap density at various steps of the solar cell fabrication process correlated with the iron content in the starting material and dropped strongly with the distance from the junctions. The traps were detected already after phosphorus diffusion and further fabrication processes varied their density depending on the initial iron content in the wafers. The results suggest that the iron-related NJV traps are formed during/after the phosphorus diffusion process. Our results could help in tailoring the solar cell fabrication process parameters to the content of contaminants in the feedstock.

[1] T. Mchedlidze, L. Scheffler, J. Weber, M. Herms, J. Neusel, V. Osinniy, C. Möller, and K. Lauer, Appl. Phys. Lett., 103, 013901 (2013).