MEng Project Proposals: Electronics

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1 Proposed Research Project (1): Controlling Light through Strongly Scattering Media (Electronics and Electrical & Systems) The project will utilize the spatial light modulator (SLM) to control light through strongly scattering media. By adjusting both phase and amplitude of light field at very high spatial resolution, we can control light on the other side of strongly scattering media such as frosted glass or biological tissue. One can create a light focused point inside the biological tissue with some feedback mechanism. The project will required strong background in control with some knowledge in optics. Proposed Research Project (2): Looking and Imaging through Frosted Glass (Electronics and Electrical & Systems) Have you ever wanted to look or image through the frosted glass? If you are good at coding and like photography, please join this exciting URECA project for a really cool technology. Scattering media do not absorb light; they scramble the light path and mesh up the spatial information of the objects behind. We will design and execute a special optical imaging system to image the scrambled light from scattering media. These images are full of speckles with very little information of the hidden object. Then we will build an algorithm to reconstruct an image and reveal the secret behind a scattering medium. The project will combine your physical experiment skills with computational coding skills. Proposed Research Project (3): Optoelectronic Devices with Colloidal Nanomaterials The research focuses on the optoelectronic devices such as light-emitting diodes, lasers, solar cells, or photodetectors with advanced semiconductor nanomaterials. In this big project, the candidates will choose some parts which includes from material synthesis, to device fabrication and characterization. Design and simulation are also the interesting parts in our project. The candidates feel free to discuss with me about the possible topics in this direction.

2 Proposed Research Project (4): Full-Visible Colour Single Material Nanocrystal Lasers Compact visible lasers would enable an extreme technology for many applications such as lighting, display, or visible light communication. Conventional solid state lasers based on semiconductor hetero-structures are technologically matured and ubiquitous but still cannot cover the whole visible spectrum. Colloidal semiconductor nanomaterials with full visible colour tune-ability offer a great solution for this problem. The proposed research aims to study both theoretical and experimental parts of the colloidal quantum dot lasers. Depending on the candidate s interests and expertise, we will focus on different parts of projects such as: theoretically modelling/optimizing nanocrystal structures for stimulated emission, chemically synthesizing colloidal semiconductor nanocrystals, building a resonant cavity to enable a nanocrystal laser by micro-fabrication techniques, characterizing the optical gain materials and lasers. Proposed Research Project (5): MID-INFRARED PHOTODETECTORS WITH COLLOIDAL QUANTUM DOTS The research aims to develop mid-infrared (mid-ir) photodetectors at room temperature by utilizing novel mid-ir semiconductor nanocrystals. With quantum confinement effects, semi-metal materials (no or very small bandgap) such as HgTe, HgCdTe (MCT) and SnTe at the nano-meter scales can open the gap (the semiconductor bandgap) which is tune-able through a very large range of infrared spectrum only by controlling the size in a simple synthesis process. Unlike epitaxial growth approach where the quantum dots are sparse epitaxial islands spontaneously formed on a crystal surface, the CQDs are synthesized in large quantity then packed in extremely high density without coupling to phonons of surrounding matrix. The highly packed absorption materials together with semiconductor like bandgaps, their mid-ir photodetectors performance will be significantly high.

3 Proposed Research Project (6): Light Engine with Digital Micro-Mirror Devices (Electronics and Electrical & Systems) The project will utilize the Digital Micro-Mirror Devices (DMD) to modulate the light intensity at high spatial resolution. Various techniques in display technology will be considered to enhance the frame rate of projector and increase the bitdepth of grey images. The light engine will be able to create arbitrary grey images at very high resolution for display technology. When combining with specific laser light (usually UV light), the light engine will be used in 3D printing technology as resin curing machine. Proposed Research Project : Fan Weijun ewjfan@ntu.edu.sg Optimization of Ge on Si semiconductor quantum well laser Ge on Si quantum well laser structure will be designed and optimized to meet desired 1.55 um wavelength and achieve the maximum optical gain using our existing k.p software. Band structure parameters and optical gain will be calculated. The influence of number of quantum wells on optical gain will be studied.

4 Proposed Research Project (1): Poenar Daniel Puiu Microfluidic in vitro model of epithelial cells & their tight junction assessment The lining of the gastrointestinal tract (GIT) is the largest surface exposed to the external environment in the human body where the absorption of food and drug takes place. Understanding the mechanism of compounds absorption through the small intestinal epithelium, and how specific organs respond to these compounds is critical for toxicological evaluation of new drugs and food screening. Additionally, the mechanism of intestinal barrier modulation and its transport function is of high importance for nutrition, pharmaceutical and pathological sciences to understand the diseases pathogenesis and the development of new therapeutic approaches. The epithelial cells act as a selectively permeable barrier (permitting the absorption of nutrients, electrolytes, and water while maintaining an effective defense against toxins) and their permeability depends on the regulation of the intercellular tight junctions (TJs) between them. This barrier function is severely compromised when epithelial cells (ECs) are lost, for example, after exposure to microorganisms, and their products. This project will investigate the role of the epithelial barrier in transportation of pharmaceutical and biological compounds through the intestinal lumen. For this purpose, an in vitro model of the intestinal lumen -comprising a monolayer of epithelial cells (ECs) and a lining mucus layer produced by mucus-producing cell co-culture- will be integrated within a three-dimensional (3D) microfluidic biochip. To achieve this goal, the student will perform first a Literature review, design the 3D microfluidic structure of the biochip with integrated sensors and perform various FEA simulations to optimize its performance, design the fabrication process and assist in the fabrication of the devices, and finally test & measure them. The project will be carried out in collaboration with Dr. Qasem Ramadan of the Institute of Microelectronics (IME), Singapore, who will be co-supervisor.

5 Proposed Research Project (2) : Poenar Daniel Puiu epdpuiu@ntu.edu.sg Plasma etching of dielectrics for sub-50 nm structures Scaling down devices dimensions is still the mainstream trend in CMOS technology. Ensuring the capability to perform high-precision plasma etching of dielectrics for sub- 50 nm sized structures is essential for continued miniaturization in CMOS technology. Fabricating devices with critical dimensions smaller than 50 nm is possible by using ArF-laser lithography but the role of plasma etching in this development is very critical. This is because dielectrics can be used as hard masks in the fabrication of MOS transistor gates, and this complicates the etching process, introduces additional sources of error and makes downscaling of etch windows much more difficult. Therefore, the post-etch resolution capabilities obtainable using Ar-F lithography are enhanced with additional trimming or shrinking methods. Direct Self Assembly (DSA) of block copolymers is a widely explored method to obtain patterns used as masks to etch holes or trenches. However, important challenges concerning material development, etch processes and integration still need to be addressed for full adoption of DSA in manufacturing. This project will explore other alternative ways of downscaling etch windows, based on combining two methods: 1) Controlled plasma polymerization on the resist openings sidewalls, which is followed by etching of first hard mask; 2) Shrinking the window opening in the first hard mask (Sibased dielectric initially deposited by PECVD) followed by etch back, thus leaving spacers on sidewalls resulting in reduction of bottom CD. Further stages of development will include etch optimization for bottom layer which, depending on integration flow, may serve as a functional layer or as a 2 nd hard mask. In the latter case it is planned to investigate comparatively the traditional hard mask of TiN with new hard masks such as AlN, Al2 O3 and Cr which provide very high selectivity in fluorine-based plasma and potentially allow to achieve much higher aspect ratios in the underlying functional layers. The project will be carried out in collaboration with Dr. Vladimir Bliznetsov of the Institute of Microelectronics (IME), Singapore, who will be co-supervisor.

6 Proposed Research Project : Wong Kin Shun, Terence ekswong@ntu.edu.sg Fabrication of micro structured rubber dielectric film for high sensitivity pressure sensors and their application in electronic skin The development of electronic skin which mimics the tactile sensing property of human skin is critical to the future generation of robots and medical devices. The key component of electronic skin is highly sensitive and flexible pressure sensor. Recently, the electronic skin has been demonstrated by integration of resistive pressure sensors which are driven by active matrix drivers with organic transistors. Difference than previous work, we will propose to use organic transistor itself as sensing device by detecting the changes in capacitance of the transistor. The micro structured rubber film with good elastic property will be used as a dielectric layer in order to obtain foam like structure for high sensitivity. When pressure is applied on the transistor, the changes in thickness of the micro structured dielectric layer make the changes in capacitance of transistor, in turn; the changes in source drain current can be detected. At initial, we will start with individual transistor. However, the ultimate aim is to fabricate the pixel type array of transistors to demonstrate as electronic skin. This project involves close collaboration with Dr. A K K Kyaw of ASTAR IMRE (Institute of Materials Research and Engineering).

7 Proposed Research Project : Lee, Seok Woo sw.lee@ntu.edu.sg Electrochemical systems for energy harvesting and storage The proposed research program is aimed to answer the questions of how to convert various types of energy, such as thermal and kinetic energy, to electricity and how to store and carry energy for transparent or flexible electronic systems using electrochemistry, nanomaterials, and micro/nano fabrication. Proposed Research Project (1) : Leong Wei Lin wlleong@ntu.edu.sg Studies of electrical properties of self-healable polymer dielectric Printable electronics, featured with robustness and reliable flexibility has huge potential application in various wearable and integrated electronic devices. The ability to self-heal in electronic devices, for example, cracks can close on their own, can significantly improve their reliability and lifetime. This project aims to develop self-healable materials as gate electric in transistor. Proposed Research Project (2) : Leong Wei Lin wlleong@ntu.edu.sg Metal halides based transistors: investigations of charge transport properties and device performance enhancement Metal halides materials are attracting great attention in the scientific community as they hold promise of high carrier mobility and ease of processability, combining the appealing aspects of both inorganic thin-film and organic semiconductors. Here, we will design the structure of fieldeffect transistor and determine the electrical properties of these materials. The interfacial interactions between the metal halide semiconductor and gate dielectrics which will have a profound influence on the device performance will also be studied.

8 Proposed Research Project (3) : Leong Wei Lin wlleong@ntu.edu.sg Biodegradable and Flexible Memory Arrays The development of printed, flexible and biocompatible electronics that are composed of non-toxic materials and can completely disappear in a controlled fashion after fulfilling its duty will enable many novel applications such as sensors for food monitoring and integrated health diagnostics. This project aims to demonstrate a flexible, biodegradable memory device based on bioinspired materials.