Fast Wafer-Level Characterization of Silicon Photodetectors by Photoluminescence Imaging

Hussein Ayedh*, Wisa Förbom, Juha Heinonen, Ismo T. S. Heikkinen, Marko Yli-Koski, Ville Vähänissi, Hele Savin

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

5 Citations (Scopus)
213 Downloads (Pure)


Photoluminescence imaging (PLI) technique is conventionally used in Si photovoltaics (PV) for device characterization and inline quality control, providing substantial assistance for a wafer-level process monitoring from as-cut wafers to fully fabricated devices. Surprisingly, employing this method has not spread outside PV and thus its potential remains largely
unknown in other fields. In this case study, a fully processed Si photodetector wafer, consisting of photodiodes with various sizes, has been chosen as an example to explore the potential of PLI beyond PV. First, we show that the standard PLI measurement is able to provide a high-resolution full-wafer luminescence image of the complete devices only within a couple of seconds. The image reveals various types of inhomogeneities present in the devices, such as furnace contamination and other processing induced defects. The measured data is then converted to an effective lifetime image followed by benchmarking with a conventionally measured recombination lifetime map obtained by microwave detected photoconductance decay (µ-PCD), demonstrating further superiority of PLI in terms of the spatial resolution and the
measurement time. Lastly, correlation with diode leakage current and photoresponse measurements show that PLI is able to provide useful information on the final device performance without a need for traditional electrical contact measurements. While this study has focused on Si photodetectors, the results imply that PLI has potential also in other semiconductor devices for fast wafer-level process monitoring purposes as well as for a single device characterization either before or after wafer dicing.
Original languageEnglish
Pages (from-to)2449-2456
Number of pages4
JournalIEEE Transactions on Electron Devices
Issue number5
Early online date28 Mar 2022
Publication statusPublished - May 2022
MoE publication typeA1 Journal article-refereed


  • Photoluminescence Imaging
  • Photodetectors
  • Process monitoring
  • Si
  • recombination/generation lifetime


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