■ Upconversion colloidal Nanocrystals for Nanoscale Optically-Controlled Microwave Devices

Optically-controlled microwave devices are one of the key technological components to achieve optical communication. While classical optically-controlled microwave devices exhibit excellent performance, they are costly and/or environment unfriendly involving highly toxic elements. In particular, efficient microwave devices controlled by 1.5 micron photons are highly demanded but technologically still difficult to achieve. Research and development efforts are thus desired for alternative material and device systems to expand the scope of applications of optically-controlled microwave devices. In this PhD project, we aim to develop a new type of solution-processable colloidal nanocrystals based on lanthanide-doped fluorides for alternative optically-controlled microwave devices by a hybrid device configuration. This research PhD program is located at the convergence of material synthesis, optical characterization, and device fabrication and characterization.
Lanthanide-doped fluoride-based upconversion nanocrystals represent an alternative approach to harvest near-IR photons. They have been incorporated into silicon1 and organic dye-sensitized solar cells2 leading to an extension of spectral sensitivity. Yet most of these lanthanide-doped fluoride nanocrystals can up-convert 980 nm radiation. It remains rare to obtain lanthanide-doped fluoride nanocrystals capable to up-convert in the short-wave IR spectrum range. The objectives of this work thus include (i) the synthesis of colloidal upconversion nanocrystals capable to up-convert 1.5 micron to visible wavelength by the tuning of the type and amount of lanthanide dopants; (ii) The formation of a hybrid device structure to harvest the upconversion effect of these upconversion nanocrystals. Such a hybrid device structure can be realized by the incorporation of nanocrystals into a solution-processed semiconducting polymer matrix or by their combination with MoS2-based photoconductive switches.
C. Tripon-Canseliet from the “instrumentation” will in particular bring her knowledge on the design, fabrication and characterization of nanoscale optically-controlled microwave devices She will thus supervise the optimization of nanoscale optical sources implementation in functional devices at mesoscale in order to demonstrate disruptive microwave photoconductive switching performances by direct up-converted light absorption in bulk III-V and 2D semiconducting materials. Z. Chen (from the MNC group is specialized in solution-processed nanomaterial synthesis and their optoelectronic applications. From his expertise, L. Aigouy rom the MNC group will assist in optical characterization of nanomaterials and devices.

Keywords

Photodetectors, upconversion, colloidal nanocrystals, photoconductivity, microwave switching

UMR8213 Physics & Materials

Description of the research Unit/subunit

This thesis project will be carried out in LPEM- UMR 8213. MNC group, has built up its research experience over the past few years on (i) the development of novel nanomaterials (quantum dots, hybrid perovskite halides) for photovoltaics, (ii) near-field optics with fluorescent nanoprobes, as well as (iii) micro and nanothermics (i.e.) the study of thermal properties of compounds and device with a sub-micron lateral resolution by fluorescent scanning probe microscope. All the research activity is built around the electromagnetism, from the static (electrostatics, magnetostatics) to optics through microwaves and infrared. The main research topics are: i) Electrostatic instrumentation and sensors; ii) Nuclear Magnetic Resonance; iii) Antennas, linear meta-materials, microwave propagation and sensors; iv) Infrared imaging; v) Optical control of RF nanodevices. It benefit from equipment in microwave in probe test environment as well as in free space, and in Telecommunications, infrared optics,3D full wave and analytic simulation tools, dielectric characterization, and cryogenics. LPEM has access to the shared clean room Paris Centre ensuring technological environment needed

Name of the supervisor
Charlotte Tripon-Canseliet (charlotte.tripon-canseliet@espci.fr)

Name of the co-supervisor
Zhuoying Chen ( Zhuoying.Chen@espci.fr)

Intersectoriality

This research project related KET such as nanotechnology for electronics and photonics is part of interest for Telecommunications and Defence applications such as with THALES group.
This collaborative project will help in gaining fundamental understandings on multiple aspects including material synthesis, design rules and device physics of optically-controlled microwave devices.

Interdisciplinarity

This thesis project employs a truly multidisciplinary approach in order to tackle the complex and multi-domain challenges to achieve efficient hybrid devices for optically-controlled microwave applications by the use of upconversion in nanocrystals. Specifically, this project covers domains of chemistry (material synthesis and modification), engineering (microwave device fabrication and characterization), and device physics (microwave device characterization and device modelling).

International mobility
This research activity is mainly conducted with the Nanyang Technological University (NTU) in Singapore for material synthesis of quaternary semiconductors through research agreements with CNRS labs in Singapore.

Electromagnetism, semiconducting materials knowledge
Nanotechnology technological processes tools (growth, etching, optical and E-beam lithography, material mechanical transfer)

Call for applications : from February 1st to March 31st 2019
Eligibility check results : Mid April
3i Committee evaluation results : Mid May
Interviews from the shortlisted candidates with the Selection Committee : Late June-Early July
Final results : Mid July