Integration of Silicon Germanium to a Silicon Photonics Platform

Lead Research Organisation: University of Southampton
Department Name: Optoelectronics Research Centre


The variety of SiGe compositions commonly target specific applications and most of the methods used to grow compound material only allow to achieve a single composition on a specific layer within an epitaxy process step. A novel epitaxy method based on liquid phase epitaxy (LPE) or rapid melt growth (RMG) gives the unique possibility of more than one SiGe composition across the wafer and makes possible to have more than one type of SiGe based device using just one deposition and one anneal step.
The aim of this PhD project is to use the RMG epitaxy method to fabricate waveguide integrated devices such as detector or modulator. It is expected that the RMG process will reduce the defect density and give enough good quality material for the integration. The process development and integration of the RMG method of SiGe on SOI and the fabrication of SiGe waveguides is therefore the target of the currently conducted work.

Silicon photonics is currently an expanding platform for the integration of optics and electronic circuits. In a time of increasing demand for faster and more efficient interconnects, the substantial amount of research data available for silicon in electronics facilitates the migration of interconnect technology towards CMOS compatible photonic devices and systems
Silicon germanium is a promising material for such high performance telecommunication devices. Thanks to its physical properties and fabrication methods previously demonstrated using rapid melt growth (RMG) enabling crystal composition engineering, it is possible to design cutting-edge devices with this material.
The fabrication process for the integration of the SiGe RMG to SOI to form Si to Ge and SiGe waveguides transition is in progress. Masks have been designed in order to provide enable the waveguide integration process following earlier process development tests. The new integration process being developed is an efficient and fast way to achieve this aim. This report is a review of the project progress throughout the last 8 months of my work as a PhD student at the University of Southampton within Silicon Photonics group.

Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/N509747/1 01/10/2016 30/09/2021
1921136 Studentship EP/N509747/1 04/01/2016 30/06/2019 Katarzyna Grabska
Description The SiGe structures with varied composition (multiple composition across the same sample) obtained from the Rapid Melt Growth (RMG) processed on the SOI platform.
Exploitation Route further work linked to the RMG, waveguide integration, possible patents
Sectors Electronics

Description Processing with the research paper, results presented over conferences, all described within the PhD thesis submitted last year
Sector Electronics
Description Chemical Mechanical Polishing 
Organisation VTT Technical Research Centre of Finland Ltd
Country Finland 
Sector Academic/University 
PI Contribution -
Collaborator Contribution Chemical Mechanical Polishing conducted in the clean room of VTT.
Impact Confidential agreement signed
Start Year 2016
Description Ge and SiGe deposition work 
Organisation Polytechnic University of Milan
Department Laboratory for Nanostructure Epitaxy and Spintronics on Silicon
Country Italy 
Sector Private 
PI Contribution Providing samples/ wafers for further work
Collaborator Contribution Ge and SiGe deposition and XRD measurements of the Si content
Impact still active, too early to say
Start Year 2018
Title invention related to SiGe based MOSCAP 
Description from the patent: Field of the Invention The present invention relates to silicon-based optoelectronic devices, particularly electro-absorption modulators or metal-oxide semiconductor capacitor modulators, which include inclined or angled sidewalls. Background of the Invention Photonic interconnection solutions are advantageous over conventional electrical interconnects as they generally have lower energies per bit transferred and high power efficiency at higher date transfer rates. Furthermore, through wavelength division multiplexing, photonic interconnects can reduce interconnection costs by enabling multiple data channels to travel in a single interconnect. A challenge to be solved is to fabricate micro-scale optoelectronic devices that provide low energies per bit and high power efficiency, whilst also offering high bandwidth density to exploit to the fullest potential wavelength division multiplexing. Two micro-scale optoelectronic devices of particular interest are electro-absorption modulators (EAM) and metal-oxide semiconductor capacitor (MOSCAP) modulators. EAMs generally operate through the Franz-Keldysh effect, whereby the introduction of an electromagnetic field (e.g. voltage) across a region influences the absorption of light within that region. MOSCAP modulators, in contrast, operate to influence the phase of light passing through the device 
IP Reference WO2018224621 
Protection Patent application published
Year Protection Granted 2018
Licensed No
Impact the possible further application based on the patent
Description OSA Foundation Diversity and Inclusion Grant 2019 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact Received grant was used to promote diversity and inclusion within STEM
Year(s) Of Engagement Activity 2019
Description School Visit, Science Festival with the cleanroom tour 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact Pupils (Year up to 11) attended a school visit to the research cleanrooms and laboratories where optoelectronics devices, e.g. associated with the award, are fabricated. Afterwards, discussion about research and science related was conducted. The impact of these activities was evaluated via forms filled by students at the end of the visit.
Year(s) Of Engagement Activity 2016,2017,2018
Description Woman in Optics SPIE grant 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact outreach/cleanroom visit event for the International Women in Engineering Day celebration (June 2019)
for female pupils (15-18 years old) keen on science, in order to convince them to consider a STEM based
career. This tour has been run successfully by OPSoc in the past.
- coffee and cake event with a panel disccussion about the role of woman in Optics/Science and
challengess due to a gender, for general public and the university community
- International Women's Day celebration (March 2019) with a lecture presented by a female scientist
working in the Optics
- a stand during the university's Festival of Science to inform the general public, especially primary
school children, about various women in STEAM subjects
-International Day of Light - a small art competition for female school pupils which can help to interest
them in Science
Year(s) Of Engagement Activity 2018,2019