Today’s integrated circuits contain more than a billion switches operating at gigahertz (GHz) speed. To achieve this, device, interconnect and contact dimensions are all shrunk while the chip complexity increases, leading to longer interconnect paths. Hence, the performance of electronics is increasingly being limited by the performance of interconnects. Owing to their superior bandwidth density, optical links have increasingly replaced shorter and shorter electrical links within datacenters down to the edge of the integrated circuits. Hence, photonic integrated circuits (PIC) are becoming a key contender for the next generation of communications, and more specifically for large data center related transceivers. This technology allows for integrated optic and electronic functionality combined with advanced manufacturing and delivers the required high-speed performance with scaling advantages in cost. To lower the power consumption and achieve more reliable photonic integrated circuits, both thermal management and defects control are important. At all levels of system integration from the package down to individual devices. Whereas this is true for electronics, thermal effects are even more severe for photonic devices.
The overall objectives of the action DATENE are:
* Combine the thermal and defect analysis in order to understand how material quality and defects impact thermal properties of the devices.
* How the thermal properties impact the device performance, and based upon these findings to propose novel more robust device designs.
Conclusion of the action: The project has fully achieved its objectives and milestones for the period.
* We carried out 3D thermo-electrical simulations and analyzed the defect-related self-heating effects in III-V on Si pin photodiodes and found that two types of defects are found to be present in the device and contributed to the self-heating of devices: positive oxide charges close to the interface between the III-V and the top oxide layer and the electron-type traps at the p-InP/i-InGaAs interface.
* We did systematically thermal analysis on the nanocavity lasers, including optimization of the cavity structure as well as the pumping strategy from a thermal perspective by both simulation and optical characterization. Based on the thermal analysis, we draw guidelines both on the design of the cavity structure and the pumping strategy.
* Based on the thermal analysis, we designed and fabricated the metal-clad InP nanocavity from which we are able to see the evidence of lasing on cavity size of 300 nm.
* A high-speed photodetector is demonstrated with cut-off frequency of 70 GHz and data reception rate of 100 Gbit/s. The device also performs as emitter under forward bias with emission wavelength at around 1550 nm. The thermal effects under are studied by SThM and we only see a temperature increase of 15 K.
