Silicon Modulators and Germanium Photodetectors on SOI: Monolithic Integration, Compatibility, and Performance Optimization

Si modulators and Ge photodetectors are monolithically integrated on Si-on-insulator. The carrier-depletion-type Si modulators achieved high modulation efficiency and speed ( V _¿ L _¿ = 2.56 V·cm, 10 Gb/s). Low-voltage operation ( V _RF = 1 V _pp ) was also demonstrated. Introducing a low-thermal-budget postepitaxy anneal improves the performance of the Ge photodetectors, thus resulting in significantly improved dark current. The responsivity and speed in the low-voltage regime are also enhanced, which enhances low-voltage or even short-circuit ( V _Bias = 0 V) operation.