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Flexible Hyperspectral Infrared Detectors

Periodic Reporting for period 1 - FLAIR (Flexible Hyperspectral Infrared Detectors)

Reporting period: 2016-03-01 to 2018-02-28

The ambition set out in the proposal of the FLAIR project was to introduce a disruptive concept for hyperspectral imaging, that will enable mid- and short-wave infrared signals to be recorded simultaneously using a single detector. To truly be a game changer, FLAIR needs to be designed based on cutting-edge technology offered by emerging atomically-thin (2D) materials as these will allow it to be imperceptible, flexible and durable. Combining all of these attributes, FLAIR will form a versatile platform, suitable for inclusion in packaging, and in disposable probes for medical diagnostics, as well as in robust systems such as security cameras.
To achieve these goals, the FLAIR platform is based on online modulation of the energy barriers in 2D materials, coupled with their enhanced properties of light-matter interaction. As the pool of target material expanded, broader potential for societal impact emerged, since the FLAIR detector platform could now be tailored to access a wider range in the electromagnetic spectrum.
Amongst the societal benefits offered by this novel platform, we are expecting to see emerging technologies that will allow:
1. Online, low-cost monitoring of packaging integrity for security in various sectors, ranging from food to homeland security.
2. Point-of-care diagnostics for remote and rural area, that will give reliable information and timely response to both patients and care providers.
3. Further integration with household items, to allow for secure, short-distance autonomous communication (Internet of Things).
To deliver goals set for the FLAIR platform, we have set the following objectives:
1. Develop wavelength-specific energy barriers in 2D semiconductors
2. Study the photoresponse and electrical characteristics of 2D semiconductors
The undertaken work under objective 1 led to the discovery of ultra-low energy barriers in metal-semiconductor interfaces (N.J. Townsend et al., 2D Mater. 5, 025023, 2018). Additionally, methods for the formation and measurements of low barriers in 2D semiconductors were demonstrated (F. Reale et al., Sci. Rep. 7, 14911, 2017). Indeed, both these publications represent two extremes in 2D semiconductor properties. The former exhibits the lowest ever recorded Schottky barrier which is still governed by semi-classical current injection mechanisms, while the latter demonstrate the highest recorded mobility for lab-synthesised WS2.
The work performed within the scope of objective 2 led to the creation of a novel paradigm in the field of electron dynamics, by demonstrating the effect of extremely slow carriers on the electrostatics and transport properties of surface controlled semiconductors. The primary work published under this objective (I. Amit et al., Adv. Mater. 29, 1605598, 2017) attracted the attention of the academic world.
Some of the main scientific achievements of this action were
- The discovery of threshold voltage transient effect, which is governed by extremely slow charge carriers dynamics. This effect dominates the transport properties in semiconductors in which one dimension, or more, is lower than the Debye screening length.
- The demonstration of ultra-low Schottky barriers. These results hold immense significance for the future of infrared light detectors, and also perfectly align with the original goals of the FLAIR platform.
- The fabrication and demonstration of high optical quality and high mobility CVD-grown semiconductor which is one unit-cell thick. As a derivative of this research, high quality electrical contacts to 2D semiconductors were realised.
Each of these achievements represented a significant leap from the hitherto state-of-the-art, and all of them are applicable beyond the materials that were chosen for the demonstration. As such, the outputs of this fellowship, that are applicable to 2D semiconductors at large, establish a high-quality body of knowledge that significantly affect the scientific community’s approach to 2D materials. It is of particular interest to mention in this context the development and dissemination of the Threshold Voltage Transient Spectroscopy (TVTS). This novel methodology’s impact on academic research into 2D semiconductors is twofold. First, it provides important insight into the mechanism of current evolution through dynamic capture and emission processes of charges in surface governed conductors. Second, building on the insights gained, a new method for charge traps spectroscopy, namely TVTS, was developed and demonstrated on several 2D materials. This new method of spectroscopy will enable the academic community to obtain information that is essential for developing novel devices, without the need for a large invest in equipment.
The prestigious Marie Skłodowska-Curie Actions (MSCA) Fellowship has had a major impact on the career path of the Fellow, enabling him to secure a permanent academic position as an Assistant Professor in Electronic Engineering in Durham University (https://www.dur.ac.uk/engineering/staff/profile/?id=17173) a position which he accepted directly following the completion of the Fellowship.
On a broader perspective, the work carried out has immense societal implications, as was discussed previously. While the research generally carries a more fundamental approach to science, the vast amount of knowledge gathered through this Fellowship has laid the infrastructure for achieving robust and significant technological development that are bound to follow.
Amongst the societal benefits, we are expecting to see emerging technologies that will allow:
- Online, low-cost monitoring of packaging integrity for security in various sectors, ranging from food to homeland security.
- Point-of-care diagnostics for remote and rural area, that will give reliable information and timely response to both patients and care providers.
- Further integration with household items, to allow for secure, short-distance autonomous communication (Internet of Things).
The published research outputs conform with the European Commission’s policy of open-innovation, open-science and open to the world. The high quality research strengthen the European seal of excellence, which is part of Pillar 3 – Maximising Impact, of the open-innovation theme. The publications in gold open access satisfy the open-science theme’s requirements and promote prospective collaborations from around the world.
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