The realization of a silicon optical phase shifter marked a cornerstone for the development of silicon photonics, and it is expected that optical interconnects based on the technology relax the explosive datacom growth in data centers. High-performance silicon optical modulators and switches, integrated into a chip, play a very important role in optical transceivers, encoding electrical signals onto the light at high speed and routing the optical signals, respectively. The development of the devices is continuously required to meet the ever-increasing data traffic at higher performance and lower cost. Therefore, heterogeneous integration is one of the highly promising approaches, expected to enable high modulation efficiency, low loss, low power consumption, small device footprint, etc. Therefore, we review heterogeneously integrated optical modulators and switches for the next-generation silicon photonic platform.

We successfully demonstrated a 2T0C-FeDRAM with a record-long multibit retention time exceeding 2000 seconds and 4-bit (19 states) capability, attributed to a V_SN of 0 V leveraging the non-volatile properties of ferroelectrics.

We demonstrate the programmable light intensity of a micro-LED by compensating threshold voltage variability of thin-film transistors by introducing a non-volatile programmable ferroelectric material, HfZrO₂ into the gate stack of the TFT.

The modulation characteristics of carrier-depletion strained SiGe optical modulators with a vertical p-n junction are numerically analyzed by technology computer-aided design simulation and finite-difference optical mode analysis. In addition to the strong optical confinement in the vertical direction for the fundamental transverse electric field mode, the vertical p-n junction effectively depletes the strained SiGe layer in which the plasma dispersion effect is enhanced owing to the mass modulation of holes by strain. We predict that a Si _0.7 Ge _0.3 optical modulator exhibits V _π L at 1.55 μm of as small as 0.31 V-cm at a bias voltage of -2 V, which is ~1.8 times smaller than that of a Si optical modulator. The product of V _π L and the phase-shifter loss (αV _π L) is also expected to be as low as 18.3 V-dB at -2 V, enabling optical modulation with a 5-dB extinction ratio in a symmetric Mach-Zehnder modulator.