Ang, R. C. F., Goh, J. S., Tobing, L. Y. M., Lim, L. W., Tong, A. S. K., Fong, A. W. K., Chen, Z., & Ng, D. K. T. (2026). Annealing and passivation study of germanium on silicon (GOS) mid-infrared waveguide for sensing applications. Scientific Reports, 16(1). https://doi.org/10.1038/s41598-026-35766-1
Abstract:
Germanium on silicon (GOS) is an excellent platform for non-dispersive infrared sensing (NDIR) due to its broad mid-infrared (mid-IR) transparency. However, its optical waveguide propagation loss as a photonic sensing medium and its susceptibility to oxidation are concerns to be addressed. Herein, we study the effect of annealing GOS waveguide devices under forming gas and passivation using atomic layer deposition (ALD) of aluminum oxide (Al2O3) and aluminum nitride (AlN) on waveguide loss. Our findings showed that annealing helped reduce propagation loss as high as 17x at wavelength of ~ 5.85 μm and passivation with AlN was effective in minimising oxidation of germanium (Ge) in ambient, albeit at the expense of higher waveguide loss originating from the MIR absorption in the AlN film itself. Nevertheless, these results provide insights towards improving the performance and robustness of a GOS waveguide-based sensor.
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Attribution 4.0 International (CC BY 4.0)
Funding Info:
This research / project is supported by the A*STAR - Career Development Fund
Grant Reference no. : C233312034
This research / project is supported by the National Research Foundation and A*STAR - Low-Carbon Energy Research (LCER)
Grant Reference no. : U2102d2012
This research / project is supported by the National Research Foundation and A*STAR - Low-Carbon Energy Research (LCER) Phase 2
Grant Reference no. : U2303D4001
This research / project is supported by the A*STAR - NA
Grant Reference no. : C220415015
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