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PhD Project Proposals (Microelectronics)

Staff Name: Fan Weijun

Email: [email protected]

Proposed Research Project (1): Fabrication and PL/PLE study of Ge-on-Si photonic materials

Description:

The impressive advances in Si-based microelectronics have continuously stimulated intense research efforts to develop optoelectronic solutions that can be integrated with Si technology. Recent research results show that Ge-on-Si is a promising candidate for the Si based laser diode potentially used in OEIC. In this project, we will use spurting method to deposit Ge-on-Si material and do post annealing to improve the material's quality. And use PL and PLE to investigate the materails' optical properties.

Staff Name: Fan Weijun


Proposed Research Project (2): Design of tensile strained Ge-on-Si laser

Description:

The impressive advances in Si-based microelectronics have continuously stimulated intense research efforts to develop optoelectronic solutions that can be integrated with Si technology. However, Si and Ge are indirect band gap semiconductors, which hinder their application to active devices in optoelectronic area. Several methods have been adopted to obtain Si-based optically active materials, such as exploiting erbium doping, nano-structure materials, hybrid III-V on Si systems, etc. Recently, Liu et. al. reported a novel tensile-strained Ge-on-Si laser operating at room temperature. To obtain efficient light emission from the direct gap transition of Ge, heavily n-type doping has been combined with 0.2-0.3% tensile strain in Ge. In this project, we will develop a method to simulate such type laser to investigate the strain and doping effect.

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Staff Name: K Radhakrishnan


Proposed Research Project (1): High Electron Mobility Transistor Structures for High Power RF Devices using Gallium Nitride based wide bandgap Semiconductors on Silicon

Description:

Epitaxial growth (Molecular Beam Epitaxy and Metalorganic CVD) of novel GaN-based heterostructures on silicon as low-cost solution for high speed and high power RF devices. Novel stress mitigation techniques to grow crack-free layers. Advanced electrical (Hall, I-V, C-V) surface (AFM), structural (XRD, TEM) and optical (Photoluminescence, Raman) characterizations to assess the quality of layer structures. Submicron HEMT device fabrication and DC and RF characterization. Strong interest in semiconductors and materials science is advantageous.

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Proposed Research Project (2): Studies on epitaxial growth and characterization of lattice matched InAlN/GaN Heterostructures on silicon for high power applications

Description:

GaN-based wide band gap semiconductors are attractive for light emitting diodes, solar cells and ultraviolet photodiodes applications. They are also of interest for wireless network base stations, satellite communication systems and compact digital radar applications where GaN-based devices can multiply the efficiency of amplifiers. However, improvements in GaN-based High Electron Mobility Transistors (HEMTs) are limited by the fundamental parameters of established AlGaN/GaN heterostructures. The objective of this project is to explore new heterostructures using InAlN/GaN alloys and enhance the potential power density of HEMTs. InAlN alloys are attractive due to their wide bandgap (0.6 to 6.2 eV) and lattice matching capability with GaN. Extremely high electron gas density coupled with polarisation fields in the heterojunction offers power densities of 30W/mm at 2 to 12 GHz. The research will focus on optimizing the growth of InAlN /GaN HEMT layers on Si using Molecular Beam Epitaxy (MBE) and/or metalorganic vapour deposition techniques to demonstrate high performance HEMT devices. Since MBE is a low temperature process, it offers great control over the growth and composition for In-based alloys. A novel 2-step approach (low/high temperature) will be used to avoid the formation of amorphous layer as well as metal-Si clusters on the interface between the substrate and the epilayer. This approach is expected to prevent the metal diffusion into the buffer layer and reduce the defects and the integrity of buffer layers for devices. MOCVD growth is attractive for higher throughput and the ability to grow on large area substrates. However, growth of ternary indium based alloys may be challenging by MOCVD as the growth takes place at elevated temperatures leading to phase separation. Novel layer structure design and growth optimization studies will be conducted to address this issue. Advanced microscopic and spectroscopic characterization techniques including electrical measurements such as RHEED, AFM, Hall, XRD, TEM, SEM, Raman, etc will be used to analyse the heterostructures and assess the composition, thickness, electrical, surface and structural properties of the layer structures.

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Proposed Research Project (3): Gallium Nitride -based Ultraviolet (UV) photodetectors on Silicon

Description:

UV detectors have several applications such as UV imaging, solar UV measurements, flame sensors, missile plume detection, spatial optical communications, biological and chemical sensors and so on. Conventional silicon-based UV detectors have some major intrinsic limitations such as aging due to exposure to radiation of much higher energy than the Si bandgap, reduced quantum efficiency in the deep-UV range, significant loss of effective area due to the need to use filters and cooling if low dark current is required. On the other hand, Group III Nitrides offer advantages over Si for UV detection. Nitrides have a direct bandgap (which confers the photodetector with a highly improved spectral selectivity). Moreover, the photodetector cut-off frequency can be engineered by changing the mole fraction in their ternary alloys. The saturation velocity in GaN is a few times higher than in GaAs or Si, enhancing the transient response of the photodetectors. In this project, GaN-based ultraviolet (UV) detectors on Si with high performance will be developed. Compared to conventional method, GaN epitaxial growth on Si is promising and cost-effective solution, especially, such scheme has the potential advantages of monolithically integrating GaN-devices with Si-microelectronics, giving circuit designers unprecedented flexibility to use the best material and devices for each function. GaN and AlGaN layer structures of appropriate composition will be grown on Si substrates using molecular beam epitaxy (MBE). Structural, electrical and optical characterizations will be carried out to optimize the quality, composition and thickness of the layers suitable for photodetector applications. The (Al)GaN MSM (metal-semiconductor-metal) UV detectors (.<280 nm) will be designed and fabricated. The fabricated GaN/Si UV detectors are aimed to exhibit high performance such as low dark current and high responsivity. Further studies may include addressing the dark current issues using insulating layers such as ZrO2 and HfO2.

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Staff Name: Ng Geok Ing


Proposed Research Project (1): High efficient polymer based organic photovoltaic devices

Description:

Polymer-based thin film photovoltaic solar cells are important in solar cell applications. In this project polymer semiconductor/fullerene bulk heterojunction photovoltaic solar cells will be developed and characterized. The charge carriers transportation in the solar cell will be investigated in order to obtain high power conversion efficiency of the devices

Staff Name: Ng Geok Ing


Proposed Research Project (2): Control of the semiconductor nanowire growths

Description:

with one dimentional semiconductor nanostructure, semiconductor nanowires have novel electronic and optical propertis and are building blocks for developing next generation electronic and optoelectronic devices. in this project, the control of the III-V semiconductor nanowires growths will be studied. the physical properties of the nanowires will be studied and their applicaitons will be explored.

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Staff Name: Rusli


Proposed Research Project: Thin Film Si Nanowire-Polymer Hybrid Solar Cells

Description:

Organic solar cells have attracted much attention due to their solution processability and mechanical flexibility. However, their power conversion efficiency (PCE) is limited by the poor mobility of organic materials. To address this issue, hybrid cells made of inorganic nanowires (NWs), such as CdSe and ZnO NWs, embedded in a polymer matrix have been developed. SiNW(SiNW)-based hybrid cells have also been studied owing to their wide absorption spectrum, good conductivity, and excellent light trapping characteristics. Different from SiNW-based fully inorganic solar cells, the SiNW/organic hybrid cells involve low temperature and simple-solution-based fabrication processes. Therefore, they are potentially suited for the fabrication of large-area, low-cost, and yet highly efficient hybrid solar cells. SiNWs have been embedded in light-absorbing polymers, such as poly(3-hexylthiophene) and poly(3-octylthiophene). The performance of the cells has been limited by the short carrier diffusion length of 10 nm in these polymers, where most of the excitons generated will recombine before reaching the junction. Recently, a p-type polymer, poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS), has been used because of its high transparency and conductivity, leading to more efficient carrier collection. Separately, SiNWs on Si wafer fabricated using electroless etching have been directly pressed into wet PEDOT films coated on ITO glass to form hybrid cells, achieving a PCE of 5.08%. In this project, we propose to study SiNW/PEDOT cells fabricated by directly spin coating PEDOT on SiNW arrays fabricated using the electroless chemical etching technique. The focus of the project is to demonstrate such solar cells using thin film silicon instead of bulk Si wafer, so as to reduce the material and processing cost involved. A suitable structure involving thin film planar Si and SiNWs with organic material will be proposed. The photovoltaic parameters of the cells will be fully characterized in relation to their structural parameters.

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Staff Name: Sun Chang Qing


Proposed Research Project: Exploring the mysteries of water and ice for bio-medical applications

Description: Using FTIR and DFT computation to examine the length-stiffness relaxation dynamics of hydrogen bond in water interacting with drugs.

Staff Name: Tan Chuan Seng


Proposed Research Project (1): Germanium – Breathing in new life for the semiconductor industry via heterogeneous integration with silicon

Description:

The first transistor was invented using germanium (Ge) at Bell Labs and not the mainstream silicon (Si). It is ironic that for many years we abandoned Ge in IC application due to its poor surface property and other manufacturing challenges. The reality is that despite a number of shortcomings, Ge out-performs Si in terms of electrical and optical properties. Ge has higher carrier mobility compared to Si which means that Ge transistor can process data at higher speed. In addition, Ge absorbs light with wavelength suitable for optical communication, an advantage not found in Si. In the past few years, there is strong interest to integrate Ge on Si for various electronics and photonics applications as we learnt how to control its property better. It is clear that the only way to utilise Ge is to integrate small amount of Ge on matured Si wafer to make it manufacturing worthy and cost effective. Ge integration on Si is faced with the challenge due to the difference in the atom size of both materials. When a thin layer of Ge is deposited on Si wafer, undesired crystal defects are formed in the Ge layer which negates the advantages of Ge. In this project, a method of Ge on Si integration is developed using chemical-vapour deposition (CVD) with the aim to achieve reasonable quality for electronic and photonic applications. When Ge/Si with the desired properties is obtained, it electrical and optical properties are studied by fabricating active devices. The project covers materials study, growth/fabrication, and device characterization. Post-PhD prospect includes research institute and industry such as IDM or foundry.

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Staff Name: Tan Chuan Seng


Proposed Research Project (2): 3D IC Technology for Mobile Application

Description:

When Apple launched iPhone5, a lot was said about its wider screen that allowed better user interface. One thing that is more subtle is that the larger size means that it is now possible to assemble more components for better performance and functionality. The reality is that, a smart phone must not increase in size indefinitely (else risking becoming an iPad!) but at the same time needs to deliver performance and more functionality that satisfies insatiable demand from the users. This seemingly conflicting requirements means that putting the components side by side on a planar platform will run out of steam soon. A more intelligent, and straight forward, way is to integrate or assemble multiple components in a vertical stack known as 3D IC. In its core, 3D IC represents a stack that consists of multiple thinned IC that are mechanically bonded and electrically connected. This simple idea solves not only the form factor challenge, it also eliminates long and bulky inter-chip connection that is a source of parasitic that leads to unnecessary signal delay and power consumption. In 3D IC, inter-chip connection is accomplished via much shorter vertical connection known as through silicon via (TSV) that can be made in much higher density. This means faster communication at lower power (hence longer battery life) and improves the bandwidth by many folds which is critical for applications such as graphic. In this project, critical enabling technology for 3D IC such as TSV and micro-contact are developed and refined specifically for mobile application. It entails investigation of electronic materials, semiconductor fabrication technology and physical characterization. You have the opportunity to conduct research in NTU and ASTAR state-of-the-arts clean room. Post-PhD job prospect includes research institute and industry such as IDM, foundry or OSAT.

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Staff Name: Tan Ooi Kiang


Proposed Research Project (1): Integrated indoor air quality sensors with SnO2 nanorod arrays

Description:

Volatile organic compounds (VOCs) exist widely in the indoor environment. Indoor air quality (IAQ) has received much attention because of the very important role indoor environment plays on human health. In Singapore, the current air-conditioned buildings with all year around are especially vulnerable for contamination because the central air conditioning can spread the released agent from one location to the whole indoor environment within a short time period. IAQ sensors are especially important in early detection and warning to improve the built environment safety. Therefore, the development of new sensing technologies, economic and reliable comprehensive IAQ sensors become promising. The 1D SnO2 nanostructures are believed to be most promising building blocks to develop a new generation of metal oxide gas sensors. However, one issue that impacts the scale-up of nanostructured sensors is the fact that most of 1D SnO2 nanostructures fabricated by bottom-up technologies are usually randomly oriented with mixtures of several distinctly different morphologies, so innovative post fabrication strategies are required to align and connect these nanostructures during the fabrication of sensor devices. Thus, gas sensors based on individual 1D nanostructures are difficult to mass produce, which is a major obstacle limiting their practical applications. Our SnO2 nanorod arrays grown by PECVD are compatible with microelectronics process and sensor arrays have been fabricated with microhotplate on wafer level. In this work, MEMS MOS IAQ sensor arrays will be developed based on our SnO2 nanorod arrays for the realization of low-cost, low power consumption devices with high sensitivity and enhanced selectivity. Selective surface doping and modification on individual sensor groups will be carried out to improve the sensitivity and selectivity to different pollutants groups.



Proposed Research Project (2): Indoor Air Quality Control and Vegetable Plant Growth for Vertical Farming

Description:

This is a study of the emerging Advanced Oxidation Technologies in indoor air quality control for the degradation of volatile organic chemicals and biological contaminants. The innovative use of LED lighting system for simultaneous indoor Photocatalytic Oxidation and for leafy plant growth in indoor vertical airoponic farming will be investigated.

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Proposed Research Project (3): Visible-light driven nanomaterials for indoor photocatlayitc applications

Description:

This is a study of Visible-light driven metal oxide semiconductor nanomaterials for indoor photocatlayitc applications. The work involves material synthesis and characterization, and photocatalytic testing with indoor type of lighting conditions for both the degradation of volatile organic chemicals and biological contaminants. Further development into thin film coatings will be investigated for practical applications.



Proposed Research Project (4): Study of visible-light driven nanomaterials for indoor photocatalytic applications

Description:

This is a study of visible-light driven metal oxide semiconductor nanomaterials for indoor photocatalytic applications. The work involves material synthesis and characterization, and photocatalytic testing with indoor type of lighting conditions for both the degradation of volatile organic chemicals and biological contaminants. Further development into thin film coatings will be investigated for practical applications.

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Proposed Research Project (5): Indoor air decontamination by TiO2-based nanocolumn arrays

Description:

Since modern people spend ~90% of their time at home or in an office, long-term exposure to indoor chemical contaminants, including by-products of the combustion (NO2, SO2, CO, etc.), cigarette smoke, particulate matter, and volatile organic compounds (VOCs) in the indoor environment, can contribute to Sick Building Syndrome, resulting in loss of productivity and excessive medical costs. In spite of the very low concentrations, some of these compounds like NO2 or CO are extremely toxic, while some others, like benzene and formaldehyde, were proved to be carcinogenic. Therefore, the improving the IAQ is of paramount importance. Photocatalytic oxidation (PCO) air cleaning is a promising technology suitable for the elimination of a broad range of VOCs. It can decompose a broad spectrum of VOCs containing multiple chemical functionalities, including several that are poorly removed by other methods. The key issue in the photocatalytic removal of VOCs under visible light lies in the extension of the absorption threshold of TiO2-based photocatalyst. In previous works, uniform nanorod and nanocolumn arrays have been grown by us, and excellent photochemical properties were demonstrated. In this project, surface modification and functionalization of these nanostructures will be conducted to improve the PCO performance under normal indoor illumination. The synthesis equipment, various light sources for PCO, IAQ measurement system and some other facilities are available in our group. The candidate will work closely with a team with experienced professors, scientists and engineers from NTU and SIMTech.

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Staff Name: Tang Xiaohong


Proposed Research Project (1): Development and Characterization of the Polymer-based Thin-film Photovoltaic Solar Cells

Description:

Polymer-based thin film photovoltaic solar cells are important in solar cell applications. In this project polymer semiconductor/fullerene bulk heterojunction photovoltaic solar cells will be developed and characterized. The charge carriers transportation in the solar cell will be investigated in order to obtain high power conversion efficiency of the devices.

Staff Name: Tang Xiaohong


Proposed Research Project (2): MOVPE growths of narrow bandgap semiconductor alloys for mid-infrared photonics

Description:

Powerful and easy-to-use lasers operation in the mid-infrared (IR) range, 2 �m to 4 �m, are very important for a variety of military, biomedical, environmental and industrial applications, including range-finding, laser surgery and remote trace-gas sensing, etc. In this project, MOVPE growth of high quality III-V semiconductors for mid-IR photonics applications will be investigated and studied.

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Staff Name: Tay Beng Kang


Proposed Research Project (1): Carbon Nanotubes Arrays for Field Emission Applications

Description:

Aim of the project • Develop field-emission cathodes technology based on carbon nanotubes array • Investigate the interface between carbon nanotubes array and substrate by using metal silicides as a transition layer Proposal and its Significances: With the rapid development of communication and information technology, emerge a task of creating of electronic active devices, capable to operate at frequencies of the order of 1012 Hz. Unfortunately, due to several physical phenomena in semiconductors, (e.g., saturation, drift velocity and accumulation of minority carriers) solutions of these problems is challenging. Carbon nanotubes are a choice for field emission cathodes due to their unique combination of electrical, chemical, optical, thermal and mechanical properties. Despite the relatively high work function (about 4.7 eV), the important properties of carbon nanotubes for use as field emission cathodes are high electrical conductivity and an unusually high emissivity thanks to their quasi-one-dimension structure and high aspect ratio. However, studies have shown that the electron emission threshold current is only 1 mA cm-2, before burn out. Investigation into the failure mechanism shows that the main cause of degradation is the peeling of carbon nanotubes from the substrate due to insufficient adhesion of the cathode structure to the initial substrate. To resolve this issue, the interface between CNT and the existing substrate must be investigate. The use of metal silicide is a proposed to improve adhesion of carbon nanotubes to improve the threshold current. In this way, by resolving the problem of adhesion will open the way to a massive use of carbon nanotube based field emission cathodes with field-emission current densities up to tens of A/cm2 for a wide range of instruments and devices of micro-and nano-electronics.

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Staff Name: Tay Beng Kang


Proposed Research Project (2): Synthesis of carbon nanotubes and carbon hybrids nanostructures

Description:

Aim of the project • Synthesis of arrays of vertically and horizontally aligned CNTs by the CVD method with a localized and volatile catalyst to achieve high electrical conductivity, optical transparency, as well as high emission properties. • Investigate the key parameters for influencing the growth of CNTs, and hybrid nanostructures • Development of physical and chemical models for the growth process of hybrid nanostructures Proposal and its Significances: Carbon nanotubes possess many interesting and excellent properties for various applications. However, to achieve carbon nanotubes growth in the vertical and horizontal directions is challenging. One solution is to incorporate carbon nanotubes with different carbon families such as graphene to form carbon hybrids nanostructures. The growths of hybrids nanotubes have been successfully demonstrated, but the physics for the growth process are still unclear. It is therefore necessary to investigate the growth of carbon hybrids nanostructures to come up with physical and chemical growth models to create many other interesting nanostructures, and even on substrates such as metal or metal silicides. These hybrids nanostructures will lead to possible application in field emission, high-efficiency functional layers of organic solar cells and solar cell applications, as well as supercapacitors.

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Staff Name: Tjin Swee Chuan


Proposed Research Project (1): Microfiber Bragg grating Biosensor

Description:

Fiber Bragg gratings (FBGs) are widely used in telecommunication and sensing due to their excellent properties such as all-fiber nature, low cost, small size and compatibility with fiber-optic networks. A Bragg grating inscribed in a standard single-mode or multi-mode fiber having a cladding diameter of 125 µm has already been well studied in last twenty years. However, a Bragg grating written in a microfiber with a diameter of several micrometers is beginning to attract much interests in the recent months. We have successfully fabricated a microfiber Bragg grating (MFBG) using a KrF excimer laser using the phase mask technique. Unlike the conventional FBG written on a normal communication fiber, two separate reflected peaks, with a spacing of tens of nanometers in air and at room temperature, are obtained in the MFBG. The reflected peaks shift by different amount, and hence exhibit different sensitivities to changes in the refractive index (RI) of the medium surrounding the microfiber, but shift by similar magnitude with changes in the ambient temperature. These varying sensitivities of the two reflected peaks to the two parameters will enable us to determine RI and temperature of the surrounding medium simultaneously using the same sensor head. This project aims to investigate the sensing property of an MFPG for biosensing of specific markers relevant to clinical practise.

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Staff Name: Tjin Swee Chuan


Proposed Research Project (2): Microfibre Sensor for Environmental Sensing

Description:

Recently refractive index sensors based on optical microfibers have attracted increasing attention since they have large evanescent field, high nonlinearity and low-loss interconnection to single-mode fiber. Fabrications of the microfiber are commonly done by heating a standard fiber using a flame while at the same time pulling the fiber. By controlling the temperature of the filament and the pulling speed, we can fabricate either abruptly or smoothly tapered microfibers with uniform waists. In our lab, we have investigated a non-adiabatically tapered microfiber sensor and achieved ultra-high sensitivity for refractive index of the external medium. Such non-adiabatic taper has abrupt change in diameter so that it can excite higher-order modes. Due to the large evanescent field of microfiber, changes of the refractive index of the external medium will cause the coupling condition between the higher-order mode and the fundamental mode to vary, resulting in a wavelength shift. Our experiments show that the high sensitivity of microfiber sensor in the refractive index range from 1.3337 to 1.37 could have great potential in environmental sensing applications such as monitoring of contaminations in reservoir water. In this project, the student will be working with colleagues from NEWRI to develop sensors suitable for use in the field. This includes the experiment to develop the optical technique, design of a suitable optical fibre and laboratory tests in comparison to the standard laboratory instruments.

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Staff Name: Wang Qijie


Proposed Research Project (1): Design and Fabrication of Plasmonic and Metamaterial Devices

Description:

Confining and controlling electromagnetic waves at dimensions much smaller than the wavelength are of great importance for miniaturization of optical-integrated devices and improvement of the spatial resolution in optical imaging. A variety of artificially fabricated sub-diffraction-limit plasmonic [1] and metamaterials [2] devices have been demonstrated in the optical region recently. The electromagnetic response properties of these devices can be designed at will, thus bringing various unprecedented functionalities into reality. In this project, the student is going to focus on the design and modeling of those metamaterials and plasmonic devices at various wavelength regions, which have great potential for different applications, such as super-resolution imaging, biomedical imaging, nanolithography, integrated optics, etc. The candidates are expected to have knowledge in optics and photonics, electromagnetic waves, and strong interests in modeling with commercial software. If time allows, the candidate will also learn how to fabricate those devices with nano-fabrication techniques, such as e-beam lithography, with the state-of-the-art cleanroom fabrication facilitates in Division of Microelectronics. After completing the project, the candidate will have extensive experience from theory to fabrication to final characterization of those advanced photonic devices, and learn the fundamental physics behind them. 1. E. Ozbay, Science, 311, 189-193 (2006). 2. D. R. Smith, et al. Science, 305, 788 (2004).

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Staff Name: Wang Qijie


Proposed Research Project (2): Mid-infrared and Terahertz Quantum Cascade Lasers

Description:

Quantum cascade laser (QCL) is a new class of semiconductor laser based on multiple quantum wells/barriers designed to emit light in the mid-infrared and Terahertz ranges, roughly from 3 – 300 �m. Because the emission wavelength of this device is not determined by the bandgap of the material but by suitable engineering the thicknesses of those multiple quantum wells/barriers, it has been widely used to generate arbitrary wavelength emission in the mid-infrared and Terahertz for various applications, including but not limited to, sensing, spectroscopy, imaging, atmosphere monitoring, security and defense, astronomy science, and free-space communications. This project aims to study both theoretical and experimental parts of the QCLs. Depending on the candidate’s interests; we will either focus on bandstructure design of the active regions of QCLs or micro-fabrication/characterization of those devices. The motivated candidate is expected to have some basic knowledge in lasers and optics and photonics. After completing the project, the candidate will gain extensive experience on semiconductor micro fabrication, electrical and optical characterization of semiconductor devices/lasers, and fundamental physics behind it.

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Staff Name: Wong Kin Shun, Terence


Proposed Research Project: Thin film copper oxide heterojunction solar cell with plasmonic nanostructures

Description:

Copper oxide is a promising semiconductor material for photovoltaics because of the ease of deposition, low cost and abundance of copper and oxygen. It is also unique in that it exists in two crystalline forms (cuprous and cupric oxide) with different band gaps that allows fabrication of heterojunction devices from the same elements. Despite this, current copper oxide PV devices have low efficiency. In this project, a magnetron sputtering method will first be used to deposit cupric oxide and the mechanism of p-type doping will be investigated by electrical characterization. Heterojunction PV devices will be fabricated using both n-type Si and transparent conducting oxide substrates. The PV performance will be studied using I-V and external quantum efficiency measurements. In order to further enhance the light absorption, light trapping by incorporated plasmonic nanostructures will be studied. Both metallic nanoparticles with surface plasmon resonance and grating structure with surface plasmon polariton will be investigated by electromagnetic simulation and experiment.

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Staff Name: Zhang Qing


Proposed Research Project (1):

Optical resonators for ultrasensitive optofluidic nanobiosensors (Supervisor: A/P Poenar Daniel, Microelectronics Division – Project YET to be approved!)

Description:

As medicine and biochemistry make rapid steps in elucidating life's mechanisms, phenomena and interactions at nanoscale and events at biomolecular level become an increasingly important field of study. At the same time, there is an increasing demand for miniaturized, easy-to-use, low-cost and portable lab-on-a-chip (LOC) mini- or micro-systems which can provide multiplex diagnostics at the point-of-care far away from high tech laboratories and hospitals. The project will investigate the design & usage of optical microresonators (OMRs) in biochips for photonic-based micro- & nano-fluidic sensing of nanobiocomponents, namely protein-based cancer biomarkers. The main focus of the project is to design, simulate, optimize, fabricate & test optical resonator-based devices for direct sensing of nanobiocomponents in aqueous samples by ingenious combination of photonics and nanofluidics. For this purpose, the activity will be carried out in the following key areas: 1) Design of ultra-high Q factor OMRs, first for operation in NIR, then in the visible range, and also in device structures combined with microfluidics & nanochannels; 2) Study the combination of OMRs with interferometric structures integrated on-chip, such as Mach-Zehnder interferometer (MZI) for differential measurement that subtracts the effects of thermal drift and of the carrier liquid, increasing sensitivity and the signal-to-noise ratio; 3) Investigate the Application of electroosmotic flow to manipulate nanobiocomponents and actuate fluids through nanochannels. Pre-requisites for the candidate: - Should have good grades during his under- & post-grad studies, - Should preferably have a M.Sc. or M.Tech. degree (graduated, or to be awarded soon), - Strong background & knowledge of optics/photonics, particularly optical resonators, interferometric structures & lasers, - Very good hands-on skills and capability to make optical set-ups.

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Staff Name: Zhang Qing


Proposed Research Project (2):

Design of micro-electromagnetic components for NMR (Nuclear Magnetic Resonance) microspectroscopy (main supervisor: A/P Poenar Daniel, Microelectronics Division); co-supervisor: A/P Sheel Aditya, Division of Communication Engineering)

Description:

Magnetic Resonance Imaging (MRI) technique, based on nuclear magnetic resonance (NMR), is a popular diagnostic tool. However, these machines are huge and not suitable for small biological samples. The goal of this research is to design original NMR micro-probes for performing the various RF functions. As the first step towards the goal, this project deals with design of simple inductors such as mini-coils (wire wound) and planar microcoils. Dependence of the RF performance on geometrical parameters, type of the substrate, and the fabrication method will be investigated. Novel architectures, such as 3D-like integrated inductors, may also be investigated. Some hands-on work with manually wound coils could also be carried out; first the coils could be made and characterized in EEE, and then used in the SBS for characterization of a few bio-samples. We have available dedicated licenses for Microwave Studio which is a powerful electromagnetic simulation software. The student should be knowledgeable in basic electromagnetics and physics, and have good grades.

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Staff Name: Zhu Weiguang


Proposed Research Project (1): Atomic-smooth, epitaxial Multifunctional Thin Films and Artificial Designed Super-lattices by Laser Molecular Beam Epitaxy Technique

Description:

Recently, there have been extensive research activities in nanosciences and nanotechnologies and in intensive search for new and multifunctional materials for both scientifical exploration and wide technological applications. Ferroelectromagnetism, the coexistence of magnetic and electrical subsystems, engenders the material with the “product” property, thus allowing an additional degree of freedom in design of sensors, actuators, transducers, storage memory, and many electronic devices. The proposed program is aimed at experimental and theoretical development of nano-structured superlattices using the emerging L-MBE technique with atomically smoothed surface and the precisely right properties, showing the ferroelectromagnetism, the product of ferroelectricity and ferromagnetism, and spintronic effects at ambient room temperature which is over today’s state of the art. The nanostructures and interface property, electrical, magnetic, and coupled ferroelectromagnetic properties, and spin control in the structures will be systematically characterized, and prototype devices will be fabricated and tested. The new theoretic phenomena in these couple ferroelectromagnetic supperlattices will be studied from very fundamental approach, which could significantly contribute to the basic knowledge in solid state science.

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Proposed Research Project (2): Giant Flexoelectric Polarization of Ferroelectric Thin Films in MEMS Diaphragms and Applications

Description:

Flexoelectricity is a recently focused new physical phenomenon that the electrical polarization is induced by the strain gradient in solid. Flexoelectricity can exist in non-centrosymmetric material systems, it thus widely extends material choices, particularly for lead-free and environmental-friendly ones. It also exhibits anther significant feature that its coefficient is greatly increased when scaled down, especially in �m-to-nanometer range, therefore equivalent giant flexoelectric coefficient, exceeding that of popular PZT, is expected. Miniaturized MEMS devices and the state-of-the-arts laser-molecular-beam-epitaxy deposition technique will be adopted, aiming for the deep scientific understanding and the largely enhanced performance for sensors, actuators and transducers. This proposed research project therefore focuses on this dielectric coupling phenomenon of flexoelectricity in solids for its fundamental understanding in science and mechanism study, for formulating new related solid state materials with giant flexoelectric polarization to replace and/or enhance the currently dominant Pb-based piezoelectric materials, and for exploiting its huge potentials in a wide variety of sensors, actuators and transducers in commercial, military and medical applications. In this proposed research project, related fundamental science and mechanisms will be studied; the laser molecular beam epitaxy (Laser-MBE) deposition technique will be used to fabricate the extremely thin epitaxial films down to a few nanometer range with atomic smooth surfaces for such miniaturized MEMS devices, desired material systems will be studied and chosen, and MEMS type devices will be fabricated, measured and systematically investigated.

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Proposed Research Project (3): Study of Giant Flexoelectric Polarization of Ferroelectric Thin Films in MEMS Diaphragms and Applications

Description:

Flexoelectricity is a recently focused new physical phenomenon that the electrical polarization is induced by the strain gradient in solid. Flexoelectricity can exist in non-centrosymmetric material systems, it thus widely extends material choices, particularly for lead-free and environmental-friendly ones. It also exhibits anther significant feature that its coefficient is greatly increased when scaled down, especially in .m-to-nanometer range, therefore equivalent giant flexoelectric coefficient, exceeding that of popular PZT, is expected. Miniaturized MEMS devices and the state-of-the-arts laser-molecular-beam-epitaxy deposition technique will be adopted, aiming for the deep scientific understanding and the largely enhanced performance for sensors, actuators and transducers. This proposed research project therefore focuses on this dielectric coupling phenomenon of flexoelectricity in solids for its fundamental understanding in science and mechanism study, for formulating new related solid state materials with giant flexoelectric polarization to replace and/or enhance the currently dominant Pb-based piezoelectric materials, and for exploiting its huge potentials in a wide variety of sensors, actuators and transducers in commercial, military and medical applications. In this proposed research project, related fundamental science and mechanisms will be studied; the laser molecular beam epitaxy (Laser-MBE) deposition technique will be used to fabricate the extremely thin epitaxial films down to a few nanometer range with atomic smooth surfaces for such miniaturized MEMS devices, desired material systems will be studied and chosen, and MEMS type devices will be fabricated, measured and systematically investigated.

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