Parallel Heterogeneous Integration of III-V Devices on Silicon Photonic Chips

Photonics is one of the largest and fasted growing markets of the world economy. Optical technologies are key to a vast range of applications from telecommunications networks to sensor and metrology equipment and are being actively developed by industrial giants such as IBM, Intel and Cisco.

In a similar way to the evolution experienced by electronics, the demand for photonics devices with smaller footprint, lower cost and higher functionality has propelled the rapid development of integrated "photonics chips". Thanks to the legacy provided by decades of enormous investments in the electronic industry, silicon is rapidly becoming the standard material platform for photonic integrated chips. However, because of its crystalline structure, silicon is a very poor light emitter and, therefore, truly integrated devices that can emit, process and detect light on-chip still represent a major challenge. III-V semiconductor materials such as InP or GaAs provide far better performance in terms of light emission but cannot compete with silicon in terms of large volume manufacturing and cost. Combining the "best from the two worlds", i.e. heterogeneously integrating III-V light emitters on a silicon material platform, is regarded as a promising solution to circumvent the deficiencies of silicon yet keeping compatibility with industrial silicon manufacturing paradigms to allow scaling to wafer level complex products without requiring a full retooling of the supply chain.

Building on established expertise in photonic integrated devices and transfer printing technologies at Glasgow and Strathclyde universities, this proposal will develop an assembly technique to integrate active III-V membrane devices onto passive silicon photonic integrated circuits. The method will demonstrate parallel transfer of multiple devices with sub-micrometer positional accuracy and scalability to wafer-level production. The developed techniques will exploit fully back-end processes, making them compatible with current foundry standards and therefore commercial interests. Key demonstrators in optical communications, gas sensing and high density data storage will be developed to illustrate the flexibility of the methods and potential across a wide range of application spaces.

The project will benefit from the support from several academic and industrial partners who will provide resources and expertise in key areas such as wafer-scale manufacturing of III-V optical devices (CST), transfer printing system engineering (Fraunhofer), optical transceivers for telecomm and datacentre markets (Huawei), micro-assembly of active/passive photonic systems (Kaiam), integrated photonic devices for HDD data storage (Seagate), mid-IR gas sensors (GSS), large-scale silicon photonics devices (Southampton University).

The proposal aligns with EPSRC's Manufacturing the Future theme and the Photonics for Future Systems priority, and addresses specific portfolio areas such as Manufacturing Technologies, Optical Communications, Optical Devices & Subsystems, Optoelectronic Devices & Circuits, Components & Systems

The research will provide tangible impact in a number of different areas:

- Academic impact
The research is expected to generate results in key portfolio research areas such as Manufacturing Technologies, Optical Communications, Optical Devices & Subsystems, Optoelectronic Devices & Circuits, Components & Systems. The outcomes of the proposal will provide a new paradigm in integration that is directly relevant to the applications being targeted by most of these research areas. To maximise the academic impact, the outcomes of our research will appear in open-access journal papers and be accessible through the web pages of the investigators and the university libraries. Also, with the support from Fraunhofer CAP, we aim to establish a UK transfer printing capability available to academic researchers.

- Industrial Impact
The very large pool of 6 industrial partners will ensure a much valued industrial steering during the course of the project as well as an ideal vehicle to maximise the industrial impact.
We expect impact in several sectors:
(i) Information technology
There is large consensus on the fact that integrated photonic technologies will be essential to support the explosive growth of telecommunications. Specific markets that will substantial benefit from our research are those demanding large volume, low cost devices such as transceivers for data centres and optical systems for heat assisted magnetic recording in HDD. Project partners Huawei, Kaiam and Seagate are in a leading market position to maximise the impact of the research and translate it to the marketplace.
(ii) Gas sensing and monitoring
The mid-wave infrared wavelength range between 3 and 5 um is of particular relevance to sensing as it contains several important molecular fingerprints with negligible background noise from water absorption. The monitoring of gases such as CO, CO2, CH4, NH3 is becoming of increasing importance for applications in healthcare, industrial process monitoring and air quality control. For example, upcoming EU legislation on energy performance of buildings and emission control in public and private transports will demand cheap and compact CO2 sensors over very large volumes. With the support of Gas Sensing Solutions, one of the demonstrators of our research programme will be a compact CO2 sensor integrating antimonide-based LED sources emitting at ~4.2 um and a silicon spectrometer.
(iii) Manufacturing
With support from the industrial partners, we aim to progress two of the project objectives, namely the transfer printing technology and the III-V semiconductor membranes, to higher TRL levels. The expertise of CST in the manufacture of integrated III-V opto-electronic devices will offer an ideal venue for translating the III-V membrane technology to a commercial semiconductor foundry and over full wafer scale processing. The expertise of Fraunhofer in system engineering will be of great relevance for the establishment of a robust transfer printing capability.

- Researcher/student Impact
The research programme will directly train two PhD students and equipped them with the required skills to become valuable resources for UK industry. The PhD students will be exposed to a rich academic and industrial research environment and will undertake advanced level training that includes skills in distributed working, collaboration, entrepreneurship and business planning skills. The PDRAs will be encouraged to take advantage of the various opportunities, resources and support for early career researchers, such as the transferable skills training programmes that include several courses for personal, professional and career development (e.g. relating to teaching, enterprise, knowledge exchange, employability, public engagement, fellowship and proposal writing, project management).