About us

About us

Overview

TeraApps (Doctoral Training Network in Terahertz Technologies for Imaging, Radar and Communication  Applications) is an innovate programme providing a unique research training opportunity for a cohort of 15 Early Stage Researchers (ESRs) in the novel and multidisciplinary field of semiconductor terahertz technologies. The TeraApps project offers strategic training opportunities with exceptional prospects for career development in both academia and industry and a potential of dramatic impact on the imaging, radar, communications and sensing application areas for our increasingly connected and smart world.

TeraApps is a four-year Horizon 2020 Marie Skłodowska-Curie Innovative Training Network funded by the European Commission. The network is comprised of 10 internationally reputed academic and industrial Partners and 17 Partner Organisations.

Aims

The mission of TeraApps is to train the pool of Early Stage Researchers (ESR) in the design, fabrication, characterization and systems utilization of terahertz sources and detectors based mainly on Resonant Tunnelling Diode (RTD) semiconductor technology, but also on emerging novel technologies including 2D materials, and their deployment in typical applications areas such as imaging, short range wireless communications, radar and sensing. To this end, TeraApps brings together world-leading experts with key complementary skills in a multidisciplinary scientific consortium.

Training

TeraApps will provide the cohort of 15 ESRs with high quality research training opportunities, supplemented with formal training courses in the relevant fields and a wide variety of complementary training courses, colloquia and seminars. The scientific training will be carried out through well-defined work-packages, based on four key themes of semiconductor terahertz technology systems. Substantial mobility within the network will expose young researchers to complementary academic and industrial environments. By integrating the complementary, multidisciplinary, as well as inter-sectorial expertise of the partners, supplemented by those of the visiting scientists and the secondments to the full and associate partners, TeraApps will train future research leaders and contribute to strengthening Europe’s human resources and industry competitiveness in the ever-growing field of terahertz electronics and opto-electronics.

ESR projects

ESR 5 Displacement current in quantum devices at THz frequencies

Displacement current in quantum devices at THz frequencies

 

Our main research activity is based on the study of quantum electron devices with nanoscale dimensions working at THz frequencies. Our research activity covers a wide spectrum, from foundational physics till practical engineering.

 

Within this innovative training TeraApps network, our first goal is giving support to other experimental partners mainly by simulating, designing and modelling Resonant tunneling diodes. We have developed a unique simulation tool, based on time-dependent quantum Monte Carlo simulations using quantum trajectories, especially suited for engineering interpretation of quantum transport at THz frequencies. The outcome of our research activity is expected to be the comparison of experimental results with our simulated data to help in analyzing and understanding the link between quantum physical interpretation and circuit engineering models of THz devices.

 

The second goal of our research activity is proposing new electron devices, based on displacement current, working at the boundary between electronic and electromagnetic technologies. We argue that at THz frequencies the manipulation of information in nanoscale devices can be performed usign the displacement current, instead of the usual electron dynamics (ransport of energy without transit of charge). We argue that such new type of devices will offer important practical advantages such elimination of joule effects-related phenomena and improvement in device’s speed.


ESR 9 Resonant tunneling diode based optoelectronic receivers and transmitters

Resonant tunneling diode based optoelectronic receivers and transmitters

Project description

 

Resonant tunneling diodes (RTDs) have shown great potential in high frequency electronic and optical circuits. This project builds upon previous knowledge gathered on the integration of RTD double barrier quantum-well structures with a photo-detective layer to make high performance optical receivers operating at the low loss windows of the fiber optic spectrum (1300nm and 1550nm). The focus will be on understanding the roles played by each layer of the RTD-PD device, and to use these results to produce epi-layer designs which optimize the device’s performance. The aim will be to increase the responsively, sensitivity, bandwidth and speed. With enough data on various devices we also are aiming at producing simulations which will mimic actual physical device performance. These simulations will act a base, upon which more advanced applications can be investigated. The integration of RTD-PD devices with light sources (like laser diodes) to produce optical transmitters in another area of research. The fabricated devices will be integrated with laser diodes in a hybrid scheme for study purposes. The goal eventually will be to mathematically model the operation of such hybrid configuration. These transmitters show high potential in being used as RF over fiber optic transceivers, which can operate at THz frequencies. Finally, the improvement which is to be achieved in sensitivity will be geared towards the use of such devices as single photon detectors which should give cheaper alternatives to current PIN and Avalanche photodiodes in the field of single photon detection. This project is expected to deliver high quality research results which will be published in high impact journals and conferences and should contribute and add upon existing literature. We are hoping that the results obtained will find their practical use in the industry, especially in the telecommunications and medical sectors, and help in achieving the vision of Horizon 2020.


ESR 11 Development of Room-Temperature Terahertz Nano-Detectors

Development of Room-Temperature Terahertz Nano-Detectors

 

Brief overview and description:

One-dimensional (1D) nanostructure devices are at the frontline of studies on future electronics, although issues like massive parallelization, doping control, surface effects, and compatibility with silicon industrial requirements are still open challenges.

The recent progresses in atomic to nanometer scale control of materials morphology, size, and composition including the growth of axial, radial, and branched nanowire (NW)-based heterostructures make the NW an ideal building block for implementing rectifying diodes or detectors that could be well operated into the Terahertz (THz), thanks to their typical achievable attofarad-order capacitance.

 

Semiconductor nanowire field effect transistors (NW-FETs) as plasma wave or thermoelectric THz detectors will be developed during the project. Here, InAs, InSb or heterostructured InAs/InSb nanowires will be used as active channel material to design an array of 1D NW-FETs exploiting low effective mass and high mobilities materials, as well as direct coupling of the oscillating radiation field to one longitudinal plasmon mode. This work will also include the design and realisation of novel 2D material based multi-grating-gate FET structures with asymmetric unit cells to achieve plasmonic THz detection.

 

Research objectives:

1) Development of semiconductor (InAs, InSb and InAs/InAs) 1D nanowire field effect transistors (FETs) as plasma wave or thermoelectric THz detectors;

2) Development of THz plasmonic detectors based on new layered materials

 

Research skills and techniques:

  • Training in specific new areas, or technical expertise etc:

- Nanofabrication trainings:

  1. Cleanroom
  2. Elctron beam lithography
  3. Scanning electron microscopy
  4. Reactive ion etching
  5. Thermal evaporation
  6. Optical lithography
  7. Wet chemical etching
  8. Atomic layer deposition

 

- THz photonics:

  1. Fourier traform infrared spectroscopy
  2. Time domain spectroscopy
  3. Transport and optical tests

 

Expected Results:

1) NW FET responsivities > 100V/W; noise equivalent power <10-10W/√Hz, detectivities < 108cm√Hz/W; bandwidth 0.3 – 2 THz.

2) Plasmonic detectors, 1-4 THz range, increased detectivity (few orders of magnitude)


ESR 12 Functional Materials Technology

Terahertz imaging with extended functionality by tailored optical metasurfaces

 

Research Objectives

The major goal of this project is the design, development and characterisation of a compact imaging system with extended functionalities in the Terahertz range (ca. 0.1 – 10 THz). Optical metamaterials offer hereby the potential for ultra-compact & efficient optics due to their ability to superimpose multiple optical phase-functions, hence generating highly integrated optics for beam shaping of both phase and polarization. Furthermore, previously unknown phenomena based on geometric phase, negative permittivity/refractive index etc. open up completely new opportunities for functional imaging. This project strives to adapt the unique traits of metamaterials to innovate THz optics, with specific focus on functional THz imaging to obtain extended information on the imaged sample (e.g. 3-D reconstruction, dichroic imaging, etc.).

Scientific Background

The limiting factor for many optical applications of THz technology to-date is the low ratio of achievable source power to the detector’s sensitivity. Particularly more complex imaging setups that aim to exploit the unique traits of THz radiation often produce blurred images close to the noise floor due to high losses of the beamforming optics. Therefore, advanced THz imaging systems would greatly benefit from both optics based on highly efficient dielectric metasurfaces (70-90 % in most cases) as well as from the reduced number of optical components through combined functionalities, resulting in fewer reflective & absorptive losses. Consequently, this project aims to improve the performance of THz optics, while other ESRs work to improve the surrounding source and detector technology.

Methodology

As a first step, the desired optical response of our beam forming optics needs to be defined depending on its intended function. Then, the outlined setup can be simplified by integrating and combining optical components into optical metamaterials, which are consequently designed via FDTD simulations. These are then manufactured by (photo-)lithographic patterning and tested for their intended performance by high-power and broadband THz sources. Once their correct operation is confirmed, they will be employed for THz imaging with extended functionality.

Expected Outcome

The targeted output of this project is consequently a very compact, easy to handle/assemble THz imaging system (at video-rate). Particularly extended functionalities and/or imaging modes that increase the versatility of our setup by providing additional valuable information on the imaged sample are envisioned.


ESR 15 Terahertz metrology for on wafer S-parameters measurements

Terahertz metrology for on wafer S-parameters measurements

For over two decades, mm-wave electronics has been a worldwide research subject. Numerous applications are being developed in this frequency range, and several are starting to be commercialized, including non-destructive testing, automotive radars, and wide bandwidth wireless. The E-band frequencies (60 - 90GHz) are already being widely used by the industry. At higher frequencies, however, applications are still limited, mainly because it remains difficult to develop direct sources and detectors for terahertz radiation. Low power and high uncertainty in the measurements done to characterize circuits prevents for realizing more complex designs, which could in fact be applicable in many new fields (e.g. medical, tomography...).

It is in this regard that the raw performance of the measurement systems becomes as important as the calibration process to assure repeatable and accurate modeling of those device behavior. On wafer S-parameters measurements over 110GHz suffer from a lack of traceability. This is due to the growth of influencing factors, in number and magnitude. It is therefore important to improve and develop new calibration flows and new methods to quantify and reduce uncertainties.

The main objective of this project will be to develop better on-wafer calibration structures for S-parameters measurements up to 500GHz thanks to uncertainty quantification. With this first step, various geometries can be screened for their performance, with the aim of improving accuracy, ultimately leading to better device knowledge.