• 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.
