High efficiency photomodulators for millimeter wave and THz radiation

Photomodulators for mm-wave and THz radiation are an essential component for many imaging and signal processing applications. While a myriad of schemes have been devised to enhance photomodulation by enhancing the light-matter interaction, there has been less focus on the photoconductive materials t...

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Bibliographic Details
Published in:Scientific reports 2019-12, Vol.9 (1), p.18304-10, Article 18304
Main Authors: Hooper, I. R., Grant, N. E., Barr, L. E., Hornett, S. M., Murphy, J. D., Hendry, E.
Format: Article
Language:English
Subjects:
639/624/1075/1081
639/624/399/1099
639/624/400/561
Aluminum oxide
Efficiency
Humanities and Social Sciences
multidisciplinary
Recombination
Science
Science (multidisciplinary)
Signal processing
Silicon
Silicon wafers
Spatial discrimination
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Summary:Photomodulators for mm-wave and THz radiation are an essential component for many imaging and signal processing applications. While a myriad of schemes have been devised to enhance photomodulation by enhancing the light-matter interaction, there has been less focus on the photoconductive materials themselves, which are often the limiting factor. Here, we present an approach to increase the photomodulation efficiency of silicon by orders of magnitude, using post treatment of off-the-shelf silicon wafers. The increase in efficiency removes the need for bulky and costly amplified laser sources, and creates the potential for compact and cost-effective modulators for real-world applications. By passivating the surfaces of long bulk-lifetime silicon wafers with Al 2 O 3 , the recombination of the photoexcited carriers at the surfaces is mostly eliminated. This results in vastly longer excess carrier lifetimes (up to ~50 ms), with corresponding increases in photoconductivity. The resulting modulators are highly efficient, with the transmission through them being reduced from ~90% to
ISSN:2045-2322
2045-2322
DOI:10.1038/s41598-019-54011-6