Periodic Reporting for period 1 - DATENE (Defect Analysis and Thermal Effects of Nanolasers and Emitters)
Berichtszeitraum: 2020-01-01 bis 2021-12-31
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.
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.
In the DATENE project, we performed systematically thermal analysis of optically pumped InP-on-Si micro- and nanocavity lasers which is based on the combination of simulations and in-situ thermal characterization. Both the steady-state and transient simulation are carried out on nanocavities from which we draw guidelines for the nanocavity design as well as for an optimum pumping strategy from a thermal perspective. Based on the thermal analysis, we designed the metal-clad cavities and are able to scale the cavity down to 300 nm with evidence of lasing under optical pumping.
We performed a joint collaboration between IBM Research Europe – Zurich and the ETHZ and demonstrate fully waveguide coupled III-V photodetectors monolithically integrated on silicon. A cut-off frequency f3dB, exceeding 70 GHz was achieved for photodetection in reverse bias. Using grating couplers centered around 1320 nm, we evaluate the detector performance under various signal encoding schemes and successfully demonstrate data reception at 50 GBd with OOK and 4PAM. While operating the p-i-n diodes in forward bias regime, light emission in LED mode centered at 1550 nm was observed. We investigated the thermal effects of the photodiodes using the scanning thermal microscopy and an overall temperature increase of about 15 K is observed under forward bias.
Thanks to the financial support from DATENE, we published 3 Journal papers in Optics Express, Nature Communications and ACS Photonics. We presented the thermal analysis of the nanocavity lasers on international conferences: the 21st International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD), the IEEE Group IV Photonics Conference (2021) as well as the Optical Fiber Communication Conference (2021) and during the IBM 24 hours Science.
We performed a joint collaboration between IBM Research Europe – Zurich and the ETHZ and demonstrate fully waveguide coupled III-V photodetectors monolithically integrated on silicon. A cut-off frequency f3dB, exceeding 70 GHz was achieved for photodetection in reverse bias. Using grating couplers centered around 1320 nm, we evaluate the detector performance under various signal encoding schemes and successfully demonstrate data reception at 50 GBd with OOK and 4PAM. While operating the p-i-n diodes in forward bias regime, light emission in LED mode centered at 1550 nm was observed. We investigated the thermal effects of the photodiodes using the scanning thermal microscopy and an overall temperature increase of about 15 K is observed under forward bias.
Thanks to the financial support from DATENE, we published 3 Journal papers in Optics Express, Nature Communications and ACS Photonics. We presented the thermal analysis of the nanocavity lasers on international conferences: the 21st International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD), the IEEE Group IV Photonics Conference (2021) as well as the Optical Fiber Communication Conference (2021) and during the IBM 24 hours Science.
In the DATENE project, we studied the heating effects of III−V-on-Si micro- and nanocavity lasers under optical pumping. This study provides guidelines for nanocavity design and operation based on thorough thermal simulations and experimental study by using Raman characterization and PL. We believe that our findings improve the understanding of thermal effects in nanocavity lasers and we believe our methods could be transferable to other photonic devices and platforms to help guide others in device design.
In collaboration with researchers at IBM working on the PLASMIC project, we demonstrated the first waveguide coupled high-speed III-V photodiodes monolithically integrated on Si. The presented in-plane integration of the III-V heterostructure p-i-n diode self-aligned to a Si waveguide represents a new paradigm for mass production of densely integrated hybrid III-V/Si photonics schemes. Compared to previous demonstrations, we do not rely on pick-and-place methods, multi-level coupling, regrowth or diffusion for integration of doping profiles. We can leverage the self-alignment with nanometer precision of passive and active components and the in-situ growth of heterojunctions. By using the same approach for the integration of the detector and the emitter and an integration technique which enables heterojunctions along the growth direction, this approach can also be extended to an all-optical high-speed link on Si without the need for evanescent coupling.
Socio-economic impact and the wider societal implications of the project: The carrying out of this project enhanced the European competitiveness in the photonics field by drawing guidelines for nanocavity design and realizing the first waveguide high-speed III-V on Si photodetector. This project also bring the expertise of thermal management skills (including steady-state and transient thermal simulation skills as well as nanoscale thermal characterization skills using micro-Raman peak linewith) in the nanodevice filed in Europe. The research outputs from this project will enhance Europe's influence in the photonic field.
In collaboration with researchers at IBM working on the PLASMIC project, we demonstrated the first waveguide coupled high-speed III-V photodiodes monolithically integrated on Si. The presented in-plane integration of the III-V heterostructure p-i-n diode self-aligned to a Si waveguide represents a new paradigm for mass production of densely integrated hybrid III-V/Si photonics schemes. Compared to previous demonstrations, we do not rely on pick-and-place methods, multi-level coupling, regrowth or diffusion for integration of doping profiles. We can leverage the self-alignment with nanometer precision of passive and active components and the in-situ growth of heterojunctions. By using the same approach for the integration of the detector and the emitter and an integration technique which enables heterojunctions along the growth direction, this approach can also be extended to an all-optical high-speed link on Si without the need for evanescent coupling.
Socio-economic impact and the wider societal implications of the project: The carrying out of this project enhanced the European competitiveness in the photonics field by drawing guidelines for nanocavity design and realizing the first waveguide high-speed III-V on Si photodetector. This project also bring the expertise of thermal management skills (including steady-state and transient thermal simulation skills as well as nanoscale thermal characterization skills using micro-Raman peak linewith) in the nanodevice filed in Europe. The research outputs from this project will enhance Europe's influence in the photonic field.