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Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - MIRIPSHE (MID-IR Integrated Photonic Sensor for Health and Environment)

Teaser

Summary

MID-IR Integrated Photonic Sensor for Health and Environment (MIRIPSHE) address the growing demand for advanced functional materials for unparalleled bio-chemical sensing using lightwave technologies for health and environmental monitoring. The MIR band is an excellent detection window for most biochemical elements such as Amides, Lipids, Nitriles and Carbon dioxide as the absorption fingerprints of these molecules lies in the 2-10 Âµm wavelength range. Integrated Photonics platform can play a major role in the MIR on-chip chemical and biological sensing with high sensitivity.Silicon is the widely used material platform for realising electronic integrated devices (electronic Cs) using the complementary metal-oxide-semiconductor (CMOS)manufacturing technique. The progress of current MIR platforms to a complete lab-on-chip system is limited due to their incompatibility to monolithically integrate with a CMOS platform. MIRIPSHE strives to ingeniously develop a CMOS-compatible MIR optical sensor platform by functionalizing rare earth enriched chalcogenide glasses into the silicon substrate using the novel ultrafast laser plasma implantation (ULPI) technique developed at the University of Leeds (UNIVLEEDS). The sensing scheme relies on the MIR fluorescent emission of rare earth elements and their selective absorption characteristics corresponding to the molecular composition of the analytes.

The materials platform developed in MIRIPSHE would accelerate the monolithic integration of MIR photonic circuitries with the present state of the art CMOS systems. This manufacturing compatible process produced under MIRIPSHE will be easily adopted by the CMOS industries and enable the low-cost production of MIR sensors for health and environmental monitoring thereby helping society and boosting the economy. These novel materials will appeal to multi-disciplinary researchers engaged in biophotonics, medical devices and smart system development, for creating fast, precise and customer-friendly devices for sensing and diagnosis. Furthermore, the material engineering and integration process would unlock a creative and high impact research area, prospering beyond the optical interconnect technology and succeeding in the seamless integration of multiple functions (mechanical, electrical, acoustic and imaging) on a single chip, leading to the invention of more sophisticated systems that have ever been seen before.

Work performed

\"Identified the suitable chalcogenide materials for integrating with silicon and silicon compounds. Three target glasses namely Gallium Lanthanum Sulfide (GLS), Erbium-doped Gallium Lanthanum Sulfide (GLS-Er) and Erbium-doped Tellurium Zinc Sodium oxide glass (TZNEr)are fabricated and the laser ablation of these materials in a vacuum chamber under controlled process gas environment and implantation into silicon/silicon compound are tried. An effort has been made to optimise the process by varying the temperature in the range 400 C-660 C. Newly formed alloys are characterised using Raman spectroscopy, High-resolution Transmission electron microscopy (HR-TEM), TEM- EDX, X-ray diffraction (XRD) and Photoluminescence emission spectroscopy techniques. In-situ high-temperature XRD and TEM studies on a silicon compound (silica) platform are also evaluated to assess the high-temperature (300 C- 1000 C) performance of erbium-doped silicate materials. It has been observed that erbium doped silicates could withstand up to 600 C and beyond that temperature, the phase separation of the compound materials occurs. This ensures that such materials can be easily integrated with a CMOS back end of line process where the highest temperature of operation is around 400 C. The engineered material subsequently displays superior spectroscopic properties of Er3+ ions in the silicon/silicate matrix at high concentrations.

An innovative method to realise selective doping for an optical waveguide formation using shadow masking technique have tried and the direct transfer of straight channel patterns are accomplished. Also, direct etching of the silica on silicon substrates to formulate the waveguides are also achieved. Compared to the shadow masking technique, the direct etching gives precise waveguide dimensions while it is an expensive manufacturing technique. Shadow masking is low cost and also provide the versatility of selective doping.
Once an optimised patterning method and precise dimensions are obtained, this method can be further extended to realise more complicated optical nanostructures and sensor heads on silicon and silicon compounds.

Overall the preliminary results obtained under MIRIPSHE are encouraging to continue this research to develop CMOS-mid-IR photonic circuits for sensing and other applications. More time and resources are really needed to drive this research and realise the full potential of the new material engineering process and device developmental activities.

The in-situ high-temperature structural studies were published in Elsevier journal Scripta Materialia (Chandrappan, J.; Khetan,V;Murray, M.;Ward,M; Jose, G. Devitrification of ultrafast laser plasma produced glass layer. Scripta Materialia 2017,131,37-41) and a second journal paper manuscript \"\"Direct integration of GaLaS on silicon \"\" is under preparation.

The fellow has submitted an EPSRC early career fellowship application based on the initial results to advance this research and extend the integration technique to other material families including group -IV and compound semiconductors such as Ge and Sn. In this research, the fellow has proposed an international research collaboration with the University of Southampton, UK; Hungarian Academy of Sciences, Hungary; University of Stuttgart, Germany. In addition, Xterra communications, a leader in optical component and underwater communication sector, is also partnered in this research.

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Final results

This research explored a new way of integrating dissimilar materials to produce advanced functional materials for applications in communication, sensing and data processing.Under this project, an active collaboration with Optoelectronics Research Centre (ORC), University of Southampton has been initiated. This research collaboration will be extended to pursue an active research in the area of chalcogenide glass integration on silicon for developing monolithic opt-electronic platform to facilitate multifunctional and low-cost next-generation on-chip systems ( as proposed in the fellow\'s early career research fellowship). This will also help the University of Leeds to engage in evolving new material engineering techniques and manufacturing process for functional materials that will be of mutual interest. Currently, a PhD student and a Post-doc is also engaged in this research and thereby training of newly skilled man power in this technology is achieved. This will be further promoted through proposed EU/International research collaborations, and training of more PhDs/Postdocs in advanced material engineering to nurture highly-skilled workforce. However, this project is still in its developmental stage and a true impact on society might be possible only after a few more years (3-4) of focussed effort.