Periodic Reporting for period 1 - FLETRAD (Flexible and transparent platform based on oxide transistors for detection and readout of ionizing radiation)
Reporting period: 2022-10-01 to 2024-06-30
Ionizing radiation presents a known health risk, but if used controllably it can be the basis of relevant applications spanning from healthcare to civil security. Either for proper control of the dose received by patients in medical treatments or workers in radiation hazardous environments, or for high resolution imagers, proper quantification of the radiation doses is demanded. The x-ray detectors market represented 2.5 Bn$ in 2020, and flexible/wearable X-ray detectors are seen as breakthrough innovations for next-gen devices. But to date, there is not a detection technology offering a combination of conformability, portability, large active area, small interference with the radiation received, potential for high resolution and low cost/complexity. By using the patented idea of oxide transistors as direct ionization radiation detectors (ROXFET) coupled to the knowledge derived from ERC Starting Grant TREND in miniaturized oxide electronics using sustainable materials and processes, FLETRAD proposes a platform tackling all those requirements and going beyond them. It creates the breakthrough market opportunity of having a fully flexible radiation sensing platform, using seamlessly integrated oxide transistors both for sensors and electronics.
FLETRAD intends to identify the most significant market opportunities/applications for the innovative platform, fabricate/validate a prototype attractive to stakeholders, develop an IP strategy and the steps toward a business plan, including the detailed analysis of the identified business opportunities. The work was performed at CENIMAT|I3N (NOVA School of Science and Technology), in a group pioneering oxide electronics, with full support of the Innovation Research and Impact Strategy (IRIS) office at NOVA.
FLETRAD intends to identify the most significant market opportunities/applications for the innovative platform, fabricate/validate a prototype attractive to stakeholders, develop an IP strategy and the steps toward a business plan, including the detailed analysis of the identified business opportunities. The work was performed at CENIMAT|I3N (NOVA School of Science and Technology), in a group pioneering oxide electronics, with full support of the Innovation Research and Impact Strategy (IRIS) office at NOVA.
• Market research and analysis to infer on the best use cases and outline IP protection strategies for future ROXFET products – trends towards integration of dosimeters into more wearable, technologically advanced, user-friendly devices with added functionality. Modern radiotherapy techniques such as IMRT are driving the need for highly-spatially resolved, sensitive and easy-to-use 2/3D dosimeters.
• Study of different multilayered dielectric combinations and their impact on ROXFET performance – sensitivities up to 63V/Gy with 55mGy limit of detection were achieved, which is perfectly suitable for radiotherapy and radiation monitoring settings. Sensor performance and metrics are tailorable simply by changing multilayered dielectric stack;
• Investigation of the root causes of the positive gate bias stress instability, variability, and lack of reproducibility found in low-temperature TFTs making use of atomic layer deposited (ALD) Al2O3 and sputtered a-IGZO – the surface of high-quality ALD dielectrics can be severely damaged when subjected to subsequent high-power sputter depositions, which leads to a high density of carrier scattering and trapping centers at the dielectric/semiconductor interface. a-IGZO's deposition conditions must be tailored according to device structure and subsequent steps since control of oxygen and hydrogen species fully determines TFT performance and stability. Correctly designed graded active layers are simple yet effective way to boost both mobility and stability of oxide TFTs.
• Fabrication of a ROXFET array on foil, as a final FLETRAD prototype, with each pixel comprising a radiation hard select TFT plus a highly sensitive ROXFET, only differing in the gate dielectric layer and device dimensions, thus enabling monolithic integration.
As major outcomes at the completion of FLETRAD, it was possible to:
• Improve ROXFET performance and stability/uniformity/reproducibility up to a point that can be taken to reliable prototypes;
• Demonstrate integration between sensitive ROXFETs and radiation hard oxide TFTs on polymeric foils;
• Identify market opportunities for ROXFET-based products, deriving and analyzing in detail two case studies in the health sector, one with a more immediate commercialization pathway, other still requiring a longer-term path, but with a very clear competitive advantage;
• Related to the previous point, conduct a detailed prior art search and viability for patentability for the second use case, revealing a very good space for a new IP protection, that is currently underway.
• Study of different multilayered dielectric combinations and their impact on ROXFET performance – sensitivities up to 63V/Gy with 55mGy limit of detection were achieved, which is perfectly suitable for radiotherapy and radiation monitoring settings. Sensor performance and metrics are tailorable simply by changing multilayered dielectric stack;
• Investigation of the root causes of the positive gate bias stress instability, variability, and lack of reproducibility found in low-temperature TFTs making use of atomic layer deposited (ALD) Al2O3 and sputtered a-IGZO – the surface of high-quality ALD dielectrics can be severely damaged when subjected to subsequent high-power sputter depositions, which leads to a high density of carrier scattering and trapping centers at the dielectric/semiconductor interface. a-IGZO's deposition conditions must be tailored according to device structure and subsequent steps since control of oxygen and hydrogen species fully determines TFT performance and stability. Correctly designed graded active layers are simple yet effective way to boost both mobility and stability of oxide TFTs.
• Fabrication of a ROXFET array on foil, as a final FLETRAD prototype, with each pixel comprising a radiation hard select TFT plus a highly sensitive ROXFET, only differing in the gate dielectric layer and device dimensions, thus enabling monolithic integration.
As major outcomes at the completion of FLETRAD, it was possible to:
• Improve ROXFET performance and stability/uniformity/reproducibility up to a point that can be taken to reliable prototypes;
• Demonstrate integration between sensitive ROXFETs and radiation hard oxide TFTs on polymeric foils;
• Identify market opportunities for ROXFET-based products, deriving and analyzing in detail two case studies in the health sector, one with a more immediate commercialization pathway, other still requiring a longer-term path, but with a very clear competitive advantage;
• Related to the previous point, conduct a detailed prior art search and viability for patentability for the second use case, revealing a very good space for a new IP protection, that is currently underway.
The results achieved can have impact at multiple levels:
• Scientific: in collaboration with University of Bologna, a model to interpret Kelvin-probe force microscopy (KPFM) spectroscopy data on amorphous semiconductors, enabling extraction of density of states (DOS) parameters from experimental data emerged as a powerful method to test thin-film semiconductors. https://doi.org/10.1063/5.0151367(opens in new window). Additionally, physics behind behavior of multilayer gate dielectrics under radiation was clarified, allowing to understand the high sensitivity of our new ROXFETs. The same physical concepts can allow to tailor multilayer stacks to other applications. https://doi.org/10.1063/5.0189167(opens in new window);
• Societal, technological and economic: both the individual ROXFETs and integrated sensor arrays can give rise to important advantages regarding cost, user safety and comfort, particularly in healthcare applications (or even create new applications).
At FLETRAD completion, several steps were identified to advance in the commercialization pathway:
• Start immediately market validation with expert involvement
• Define a roadmap to achieve higher innovation readiness levels (IRL)
• Continue technology maturation (further characterization of specifications)
• Explore potential partners to increase access to prototyping/manufacturing infrastructure
• Fill a Business model canvas
• Define/prepare a commercialization pathway selection
• Keep monitoring IRL progress every 3 months
• Start preparing an EIC Transition application regarding FLETRAD technology.
• Scientific: in collaboration with University of Bologna, a model to interpret Kelvin-probe force microscopy (KPFM) spectroscopy data on amorphous semiconductors, enabling extraction of density of states (DOS) parameters from experimental data emerged as a powerful method to test thin-film semiconductors. https://doi.org/10.1063/5.0151367(opens in new window). Additionally, physics behind behavior of multilayer gate dielectrics under radiation was clarified, allowing to understand the high sensitivity of our new ROXFETs. The same physical concepts can allow to tailor multilayer stacks to other applications. https://doi.org/10.1063/5.0189167(opens in new window);
• Societal, technological and economic: both the individual ROXFETs and integrated sensor arrays can give rise to important advantages regarding cost, user safety and comfort, particularly in healthcare applications (or even create new applications).
At FLETRAD completion, several steps were identified to advance in the commercialization pathway:
• Start immediately market validation with expert involvement
• Define a roadmap to achieve higher innovation readiness levels (IRL)
• Continue technology maturation (further characterization of specifications)
• Explore potential partners to increase access to prototyping/manufacturing infrastructure
• Fill a Business model canvas
• Define/prepare a commercialization pathway selection
• Keep monitoring IRL progress every 3 months
• Start preparing an EIC Transition application regarding FLETRAD technology.