Semester Projects

Semester Projects (Fall 2019)

All projects can be adapted for a Bachelor or a Master level

New fabrication methods for metallic and all-dielectric nano-object arrays

Metallic nano-objects and their arrays exhibit peculiar functionalities that can be exploited in several scientific fields. Such constructs can indeed be used as catalysts for arrays of semiconducting nanowires, in light trapping and extraction systems, as efficient transparent electrodes for optoelectronic devices, and in sensing and biological applications. Their fabrication remain however difficult and costly, especially over large area substrates. In this project we propose to investigate a novel fabrication approach of these nano-structures that is simple and scalable. The objective is to demonstrate a 2D and a 3D ordered array of nano-objects using simple nano-imprint and thin-film processing approaches.

Photoconductivity and crystallization of a multimaterial photodetecting fibre device

Photodetectors are optoelectronic devices employed in a myriad of applications ranging from sensing and monitoring to optical communication receiver. The recent development of thermally drawn metal-insulator-semiconductor fiber[1] has paved a novel path towards converting light to electrical signals over kilometer length scale. Decreasing the chalcogenide semiconductor size leads to a significant improvement in sensitivity of the photodetecting device[2]. In addition, the electronic performance of the semiconducting element can be prominently improved by post-drawing crystallization scheme[3]. The aim of this semester project is to fabricate novel and high performance photosensitive fibre devices, with the aim of understanding the crystallization mechanisms, and the influences of the crystallization on device performance, using state-of-the-art characterization techniques.

[1] M. Bayindir, F. Sorin, A.F. Abouraddy, J. Viens, S.D. Hart, J.D. Joannopoulos, Y. Fink. “Metal insulator semiconductor optoelectronic fibers”, Nature, 431(2004) 826

[2] F. Sorin, A. F. Abouraddy, N. Orf, O. Shapira, J. Viens, J.D. Joannopoulos, Y. Fink. “Multimaterial photodetecting fibers: a geometric and structural study”, Advanced Materials, 19 (2007) 3872.

[3] S. Danto, F. Sorin, N. D. Orf, Z. Wang, S. A. Speakman, J. D. Joannopoulos  and Y. Fink, “Fiber fieldeffect device via in-situ channel crystallization”, Advanced Materials, 22 (2010) 4162.

Influence of the composition of polymer nanocomposites on their electrical and rheological properties for multimaterial fibre devices

Thermally drawn multimaterial fibres developed for optoelectronic applications often employ polymer nanocomposites as electrode materials, because they are compatible with the thermal drawing process thanks to their thermoplastic properties [1]. However, the conductivity of such composites is far from that of metals, and even if increasing the concentration of fillers can improve it, there is a limit at which the composite loses its appropriate rheological attributes [2]. Both the conductivity and this limit strongly depend on the morphology of the particles and how they are dispersed in the polymer matrix. In this project, the conductivity and rheological properties of nanocomposites with different fillers made from melt mixing and solution techniques will be investigated. The student will learn techniques to make polymer nanocomposites via liquid processes, to fabricate multimaterial fibers and characterize their thermomechanical, optical and electronic properties.

Experimental and modelling tools:

  • Nanocomposite fabrication by melt mixing and solution techniques
  • Multimaterial preform fabrication and thermal drawing technique
  • Optical, electronic and rheological properties
[1] S. Egusa, et al. Multimaterial piezoelectric fibres. Nat Mater, 9 (2010) 643.

[2] J. A. King, et al. Electrical conductivity and rheology of carbon-filled liquid crystal polymer composites, J Appl Polym Sci., 101(2006) 2680.

Novel fabrication approaches of semiconducting nanowire meshes

Optoelectronic devices, in which the active materials are semiconductors, are typically made using energy-intensive processes. Studies conducted in FIMAP have shown that low-cost nano-imprinting and physical vapor deposition techniques followed by a simple heat treatment can lead to well-defined arrays of nano-spheres of semiconductor. Characterisation of this nano-structure have revealed peculiar light absorption properties, which means it can be used as the building block of a photodetecting device. The aim of this project is therefore to combine this process with embossing and other deposition techniques to create such a device. The student will use nano-imprinting as well as thin-film deposition techniques, and learn optical characterization approaches of semiconducting nano-structures.

Experimental and modelling tools:

  • Thin film fabrication and nano-imprinting
  • Thermal treatment
  • Optoelectronic characterization
  • Materials characterization (SEM)

In-situ Growth of Single Crystal Semiconductor in a Multi-material Fiber During Thermal Drawing

Optoelectronic fiber devices fabricated by the thermal drawing technique are promising candidates for photodetecting, chemical vapor sensing, thermal sensing and biodetecting applications [1]. However, these devices still exhibit limited photosensitivity, low response and poor charge mobility [2] owing to the amorphous semiconducting components in these multi-material as-drawn fibers. Although post-drawing annealing treatment can improve the optical and electrical properties of the semiconductor [2], the performance of the device is still limited because of the intrinsic defects in polycrystalline materials, such as grain boundaries. Realizing large single crystal semiconductor domains along the whole fiber length has attracted much attention in our field. Traditional approaches of growth of semiconductor single crystal include Bridgman, seed-material assistance and Float Zone techniques [3]. The solidification of semiconductor during thermal drawing has the same principle with Bridgman technique. The aim of this semester project is to in-situ fabricate single crystal semiconductor during thermal drawing process by controlling the thermal gradient, the drawing speed and the pressure in the furnace. The master student can also deeply understand state-of-the-art characterization techniques, such as SEM, XRD and TEM.

Experimental and modelling tools:

  • Multi-material perform fabrication and thermally drawn technique
  • Fabrication of complex fiber device
  • Optoelectronic and optical properties
  • Materials structure characterization (X-ray diffraction, HR-SEM and HR-TEM)
[1] A. F. Abouraddy et al. Towards multimaterial multifunctional fibres that see, hear, sense and communicate. Nat Mater, 6 (2007) 336.

[2] S. Danto, F. Sorin et al. Fiber field effect device via in-situ channel crystallization, Adv Mater, 22 (2010) 4162.

[3] S. Dost and B. Lent. Single Crystal Growth of Semiconductors from Metallic Solutions (2007) Elsevier.

Pressure-Sensing fiber devices

Pressure-sensing flexible systems have drawn a lot of attention due to their wide applications in touch displays, electronic skin, health care and biomonitoring (such as pulse wave monitoring), etc. Several approaches have been proposed in recent years, such as microstructured polydimethylsiloxane films which are integrated into the gates of an array of organic field-effect transistor [1,2] and artificial skin[3]. However, these approaches are complex and costly, and especially hard to realize over large scales. In this project, we propose a novel, high efficiency, and low-cost strategy to fabricate large scale fiber devices that can be sensitive to pressure. Thermal drawing will be a preferred method to fabricate the fibers and different kinds of materials, such as metal, polymer and carbon materials will be combined to achieve the targeted functionalities. The main aim of this project is to optimize the fiber devices with respect to its structure, the material selection and processing parameters. Students will learn about pressure-sensing devices design, fiber fabrication methods as well as structural and electronic characterization tools.

Experimental and modelling tools:

  • Multi-material perform fabrication and thermally drawn technique
  • Electronic characterization
  • Mechanical properties characterization (viscosity, etc.)
  • Materials characterization (Optical Microscopy, SEM)
[1] S.C.B Mannsfeld, et al. Highly sensitive flexible pressure sensors with microstructured rubber dielectric layers. Nat Mater, 9(2010) 859.

[2] G. Schwartz, et al. Flexible polymer transistors with high pressure sensitivity for application in electronic skin and health monitoring. Nat Commun, 4(2013) 1859.

[3] D. Kim, et al. Epidermal electronics. Science, 333(2011)838.

Thermal drawing Technique for Large-Area Functional Surfaces

Thermal Drawing Technique has been demonstrated as an ideal Method for microfabrication [1][2][3]. Based on an approach developed in FIMAP, the micron and even sub-micron structures have been deployed on the surface of fibers and ribbons, and even on the internal surface of hollow-core fibers. This development has brought tremendous interest in various fields, from optics, optoelectronic to biology. The proposed project aims to establish the Thermal Drawing Technique for Large-Area Functional Surface, by fabrication a new type of preforms and by evaluating the surface adhesion of different polymers.

Experimental and modelling tools:

  • Multi-material perform fabrication and thermally drawn technique
  • Rheological measurement
  • Surface adhesion characterization
[1] Nguyen-Dang et al, Advanced Functional Materials, 27, 1605935 (2017).

[2] Nguyen-Dang, Page et al, Journal of Physics D: Applied Physics, 50, 144001 (2017)

[3] Yan et al, Advanced Materials, on line: 10.1002/adma.201700681 (2017).

Exploring a nanofabrication technique with Raman Spectroscopy

Raman Spectroscopy has proven thus far an exceptional tool for probing matter at the nanoscale in very fine ways. It can for instance provide detailed information on the various chemical bondings, whether they be characteristic of one particular chemical species or of bonding between different chemical components.

Controlled dewetting provides an interesting and efficient way to obtain ordered nanostructures of various optical materials. Combining this process with Raman spectroscopy could provide a great platform for studying two interesting concepts at the nanoscale :

-Surface-enhanced Spectroscopy, which probes the presence of specific types of molecules, with resolutions down to single-molecules.

– Nanoreactors, which can significantly enhanced the mixing between different chemical components to yield materials of high interest in infrared optics.

Basic but no advanced knowledge in optics is required at the start of this project.

Experimental :

  • Thermal Evaporation
  • Nanoimprint techniques
  • Spectroscopy (Raman/ Classic)

Generating light with nanostructures

Non-linear second or third harmonic light generation is of significant relevance in many integrated optical circuits today. Efficient signal conversion can open up new possibilities in optical computation or supercontinuum generation.

Controlled dewetting provides an interesting and efficient way to obtain ordered nanostructures of various optical materials. This process can be an efficient platform to enhance second or third order harmonics  for strong incident light beams. Beyond dewetted structures, this project will also focus on non linear light generation in particular monocrystalline systems.

Experimental :

  • Thermal Evaporation
  • Nanoimprint techniques
  • Optical Characterization

Basic but no advanced knowledge in optics is required at the start of this project.

If you are interested and want to learn more about these projects please contact Prof. Sorin.