Title:	Defect Trapping in Thin Films Probed by Frequency Domain Photoluminescence
Author(s):	B. Bérenguier, A. Asseko, J.-F. Guillemoles
Keywords:	Defects, Photoluminescence, Characterisation, Characterization
Topic:	New Materials and Concepts for Photovoltaic Devices
Subtopic:	Fundamental Studies
Event:	38th European Photovoltaic Solar Energy Conference and Exhibition
Session:	1BV.3.3
Pages:	49 - 53
ISBN:	3-936338-78-7
Paper DOI:	10.4229/EUPVSEC20212021-1BV.3.3
Price:	0,00 EUR
Document(s):	paper, poster

Abstract/Summary:

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Time Resolved Photoluminescence (TRPL) is considered as a standard technique to measure carrier lifetime in thin film semi-conductors. Nevertheless, the excitation of TRPL is sudden, short and therefore the method is focused on fast recombination processes. I case of non mono-exponential decays, the tail of the decays may contain information about shallow traps and slow mechanisms but is quite often noisy and not always considered appropriately. Another approach based on Modulated Photoluminescence, also called Frequency Domain Photoluminescence (FDPL) has been developed previously and consists in the measurement the PL signal under a modulated illumination source. Coupled to mathematical modelling, it allows for extraction of information about the recombination mechanisms including both slows time constants. Here, we present a significant upgrade to the conventional FDPL method by extending the modulation frequency range from 500 Hz to 200 MHz using a Time Correlated Single Photon Counting device, the setup being able to scan both slow and fast mechanisms. We applied FDPL to thin passivated GaAs layers, and observe V-shapes in the phases curves, which are a characteristic of shallow trapping. We also attempt to fit measurement on triple cation perovskites using the two first harmonics of the FDPL signal.