On-chip Ge photodetector efficiency enhancement by local laser-induced crystallization

Torgom Yezekyan*, Martin Thomaschewski, Sergey I. Bozhevolnyi

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Metal-semiconductor-metal plasmonic nanostructures enable both on-chip efficient manipulation and ultrafast photodetection of strongly confined modes by enhancing local electrostatic and optical fields. The latter is achieved by making use of nanostructured thin-film germanium (Ge) plasmonic-waveguide photodetectors. While their sizes and locations can be accurately controlled during the nanofabrication, the detector efficiencies are significantly reduced due to deposited Ge amorphous nature. We demonstrate that the efficiency of waveguide-integrated Ge plasmonic photodetectors can be increased significantly (more than 2 orders of magnitude) by spatially controlled laser-induced Ge crystallization. We investigate both free-space and waveguide-integrated Ge photodetectors subjected to 800 nm laser treatment, monitoring the degree of crystallization with Raman spectroscopy, and demonstrate the efficiency enhancement by detecting the telecom radiation. The demonstrated local postprocessing technique can be utilized in various nanophotonic devices for efficient and ultrafast on-chip radiation monitoring and detection, offering significantly improved detector characteristics without jeopardizing the performance of other components.

TidsskriftNano Letters
Udgave nummer18
Sider (fra-til)7472-7478
StatusUdgivet - 22. sep. 2021

Bibliografisk note

Funding Information:
The authors acknowledge the financial support from Villum Fonden, Award in Technical and Natural Sciences 2019. T.Y. acknowledges funding from MULTIPLY fellowship under the Marie Sklodowska-Curie COFUND Action (Grant Agreement No. 713694).

Publisher Copyright:
© 2021 American Chemical Society.


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