Comparative Performance Evaluation of Transparent Conducting Oxides with Different Mobilities for All-Optical Switching in Silicon

All-optical switching is an appealing approach for signal processing, optical communications or sensing systems. In this work, we compare the performance of doped cadmium oxide, aluminum doped zinc oxide, and indium tin oxide as transparent conducting oxide (TCO) materials with different mobilities in thin-film configuration integrated into a hybrid silicon photonic waveguide. Our results reveal the best operational parameters and trade-offs for enabling high-performance and energy-efficient switching by using TCOs with moderate mobility but more environmental-friendly. Extinction ratios of 10 dB $\cdot \mu \text{m}^{\mathrm {-1 {}}}$ and insertion losses of 2 dB $\cdot \mu \text{m}^{\mathrm {-1 {}}}$ are achieved by an AZO/Si amplitude switch with an energy consumption of only 90 fJ. These results reveal that cadmium-free TCO materials can also be leveraged to build high-performance all-optical switches in silicon.