SnGe Asymmetric Quantum Well Electroabsorption Modulators for Long-Wave Silicon Photonics

In recent years, SiGeSn alloys have been considered as promising materials for optoelectronic applications because they offer the possibility of a direct bandgap, and are compatible with Si-based technology; therefore, they have prospective applications such as in interband lasers and detectors, solar cells, etc. Here, we consider another possible application of nanostructures based on these materials: to extend the suite of Si-based optoelectronic devices for interband electroabsorption (EA) modulators. Using the 8-band k.p method, we have designed asymmetric double quantum wells that are optimized, by varying the well and barrier widths and material composition, to show large optical transmission sensitivity to the applied bias. Generally, these structures are useful for EA modulators in the midinfrared spectral range.