Current Postgraduates
A. MICROWAVE DEVICES AND OPTOELECTRONIC SENSORS
These projects fall into three main areas; gallium nitride-based devices; micro-machined sensors; infrared (IR) sensors and systems. Projects in the devices area involve a combination of experimental and theoretical work. Fabrication, characterisation and/or modelling of devices from all three of the sub-areas are undertaken by the MRG.
Many of the projects involve collaborative work with international researchers from University of California at Santa Barbara (UCSB), University of Illinois at Chicago (UIC), Lakeshore Cryotronics in the USA, Vigo Systems in Poland, Raytheon Vision Systems (USA), NVESD (USA), and DRS Infrared Technologies (Dallas).
GaN-BASED DEVICES
(BD Nener, G Parish, L Faraone, J Antoszewski, G Umana Membreno,)
This project aims to achieve reliable, manufacturable high performance III-nitride (GaN, AIN, InN and alloys) transistors for use in high power, high frequency applications such as radar and communication systems. The GaN-based FET technology offers significantly improved performance for applications in RF/microwave power amplifiers, high speed switching for power electronics, and operation in harsh electrically noise environments, such as the automotive industry, space applications, and switch mode power supplies. Despite rapid progress in performance, AlGaN/GaN-based transistors are hampered by a variety of impediments. Two particular thrusts of our research in this area are ion implantations and dielectrics. Ion implantation offers the potential to enable a reliable, commercially feasible fabrication technology for GaN-based electronic devices. Dielectric thin-film technologies are desired for gate-insulation and surface passivation layers to enhance the performance, and overcome present limitations, of GaN- and AlGaN/GaN-based microwave transistors for high power and high temperature applications. The third thrust is improvement in electronic properties of InN, which will enable even faster electronic devices due to the high mobility and peak velocity in InN compared to GaN.
Projects in this area include:
A.1 AlGaN/GaN Transistor Device Reliability
What are the key limitations to AlGaN/GaN device performance? This project will involve the study of degradation effects on critical device parameters such as channel properties in AlGaN/GaN field effect transistors. In particular, understanding charge distribution and behaviour at the AlGaN/GaN interface has been identified as a crucial issue by our partners at UCSB, in the path to commercialisation of microwave GaN-based transistors.
A.2 Magneto-Transport of GaN-Based Transistor Structures
Q: What makes a transistor a HEMT (high electron mobility transistor)? A: Excellent carrier transport properties. This project will involve measurement of carrier transport in FET devices, under the influence of an applied magnetic field. Current joint projects with UCSB include investigations into the effect of passivation layers such as silicon nitride, and use of ion implantation for industrial scale processing. This project is closely related to A.1.
A.3 Modelling and Simulation of GaN Devices
The AlGaN material system exhibits many unique properties that must be carefully considered in modelling device behaviour. Furthermore, as a relatively new material system, there are many aspects and parameters that are unknown or as yet unconfirmed experimentally. This project will involve development of in-house modelling packages for GaN-based devices through adaptation of commercial packages such as Sentaurus. Models developed will be used to simulate device behaviour and compare with measured results.
A.4 Electronic Biological/Chemical Sensors
This project aims to develop a novel electronic biosensor. A bio-friendly, chemically inert and stable III-Nitride-transistor-based bio/chem-sensor will be developed to detect responses to various specific compounds/chemicals , particularly through cell receptors. The ability to monitor biological and chemical signals with an electronic device is a tremendously innovative approach for cell research and process control in pharmaceutical and microbiological production, and chemical sensing applications. The primary aims are:
· Study biocompatibility between the semiconducting material used as the sensor and living cells.
· Develop and optimise electronic device structures to attach and confine the living cells to the semiconductor surface of the biosensor.
· Study the behaviour of the electronic bio/chem-sensor before and after exposure to chemicals/compounds. Identify the dominant physical mechanisms that influence the detection limit of the bio/chem-sensor.
MICRO ELECTRO-MECHANICAL SYSTEMS (MEMS)
(JM Dell, J Antoszewski, L Faraone, A Keating, M Martyniuk)
Micro Electro-Mechanical Systems (MEMS) represent the integration of mechanical elements, sensors and actuators, with photonics and electronics on a single substrate. The application of microfabrication technology, developed for the manufacture of silicon very-large-scale-integrated (VLSI) circuits, to generate miniature three-dimensional structures such as motors, gears, accelerometers and pressure sensors on the same substrate as the associated drive and sensing electronics has dramatically changed and expanded the field of mechatronics. In addition to allowing mechanical manufacture on a micro-miniature scale, MEMS technology brings the low-cost, high-throughput techniques of VLSI technology to mechanical and sensor systems. Specific applications of MEMS include accelerometers for air-bag deployment and shock sensors, micropumps for drug delivery, pressure sensors for measuring tyre pressures. The Microelectronics Research Group is working on optical MEMS technology to make optical detectors which are only sensitive over a small, electrically tuneable wavelength range.
A.5 Investigation of Chemical Sensing Technologies Based on MEMS Devices
Small, inexpensive and robust chemical sensing is now a major business, with applications from security (detection of explosives at an airport for example), to global warming (determination of total carbon in soil is important for carbon sequestration and development of carbon-credit schemes), medicine, automotive engineering, … This project will investigate the use of MEMS and some innovative properties of materials developed at UWA for applications in chemical sensing. The devices to be developed will be effectively electronic noses. This project will is quite open and could be a broad scoping study, or could investigate a particular type of device in detail. It will primarily be theoretical. Skills required for this project will be an interest in innovative technologies and the ability to mathematically model a number of different physical phenomena including optical waveguides and mechanical resonances in small structures.
A.6 Lab-on-Chip Technologies
Lab-on-chip research within MRG focuses on techniques which can allow rapid analysis of ultra-small volumes of fluid. Particle separation within the fluid is a key step required in many chemical assays of biological fluids containing cells. One approach being considered is the use of acoustophoresis on-chip (ultrasonics) to setup a standing wave within the microchannel. The acoustic pressure pushes the particles (cells) to the standing-wave anti-nodes, which can be subsequently separated/routed to a specific microchannel outlet. Our contribution is the development of techniques to enable this approach to be applied in plastics and to biological fluids such as milk, which requires the heat generated on chip to be minimized.
A.7 Mapping Micro-photoelastic-induced Changes for Characterization of Biosensors
Microcantilever based biosensors are a novel next generation approach to building high sensitivity sensor arrays. The aim of this project is to create a computer controlled system which focuses a pulsed high power laser onto an absorbing thin film. The absorbed thermal pulse is expected to cause localized thermal expansion, resulting in a propagating acoustic wave. A laser Doppler vibrometer will be used to measure the induced vibrations. After programming of the XY-motion stage and laser to map the surface, the process will be characterized to determine the magnitude of the induced thermal expansions. Using simple structures such as micro-cantilevers, the project will investigate optimal locations where the photo-induced thermal expansion can be applied.
INFRARED SENSORS
(J Antoszewski, JM Dell, L Faraone, BD Nener)
The ability of IR detectors to directly sense the thermal output of an object has found wide application in thermal imaging for medical diagnostics, bushfire detection, satellite remote sensing, search and rescue, thermal loss budget estimation, as well as the more traditional defence and aerospace applications. In addition, emerging applications of IR detectors are found in spectroscopic systems for mineral exploration, pipeline monitoring, pollution detection and identification, and gas monitoring systems. Specific examples include; detection of tumours and tissue damage, detecting illegal waste disposal by ships in harbours, preventative maintenance in electrical switchgear such as high voltage transformers. For the fabrication of sensitive IR detectors, the highest performance is achieved in devices using the semiconductor material mercury cadmium telluride (HgCdTe or MCT). There are a number of unique properties which give MCT an advantage over competing technologies, with the main advantage being the ability to bandgap engineer the material, for specific applications. The MRG has recently developed new detector structures that are at the leading edge of IR sensor technology. A large amount of research is being carried out to characterise and test the performance of new devices. Projects in this area will include:
A.8 Characterisation and Modelling of HgCdTe Photovoltaic Detectors
This project will undertake theoretical modelling and performance measurements of infrared photodiodes fabricated in the MRG laboratory. The junctions are formed using an in-house developed process, and are expected to deliver state-of-the-art performance. These detectors are employed in large two-dimensional arrays that are used for infrared imaging for applications such as night vision, surveillance, medical imaging and environmental applications. A commercial modelling package, Sentaurus Device, will be used to perform two-dimensional modelling of devices.
A.9 Characterisation of HgCdTe Heterojunction Photodiodes
This work will investigate the performance of HgCdTe photodiodes based on bandgap engineered structures. This will involve both measurements and theoretical calculations. Bandgap engineering is one of the latest methods used to improve device performance and functionality, and involves the control of material thickness down to the atomic layer level.
A.10 Noise in HgCdTe Based Photodetectors
The signal-to-noise ratio in photodetectors is a key performance parameter. The measurement of noise and the identification of noise mechanisms is a fundamental requirement in the improvement of performance. This project will look at theoretical noise models and measurement of noise. The project will use devices known as gated-photodiodes to measure and identify noise mechanisms.
A.11 Small Infrared detector arrays - applications
Small infrared detector arrays are used in a wide range of commercial applications. One of them is contactless, real time, temperature measurement. In this case the detector array hybridized with another array of micro Fabry-Perot filters represents a spectrometer with a number of preselected infrared bands Such a spectrometer can be used for the analysis of black body like radiation and in consequence calculation of the objects temperature. In this project the task will be to fully characterise the hybridized detector /filter array, collection of black body characteristics versus temperature and develop a software for fast algorithm converting signals measured from detector array to temperature. This project requires a person interested in both, the research in the field of infrared detectors and solid opto-electronic systems engineering.
B. SEMICONDUCTOR MATERIAL PROCESSES AND CHARACTERISATION
(J Antoszewski, JM Dell, L Faraone, G.Parish, BD Nener, G Umana Membreno, M Martyniuk, G. Tsen)
The MRG has some of Australia’s best facilities for undertaking materials characterisation for a wide range of semiconductors, and has developed techniques that are now licensed by large semiconductor facilities around the world. A number of projects are available in this area, working on the development of new techniques, as well as using techniques we have already established to measure the properties of semiconductor layers.
The data obtained from these measurements give information about the electrical, optical and structural properties of the semiconductor layers. This information will be used to design new growth processes and develop new electronic and sensor devices.
Students will gain experience in high technology instrumentation, low-level signal measurement techniques, and low-noise system layout. These skills are applicable in a wide range of communications and electronics areas, as well as in the mainstream semiconductor industry.
B.1 Sensitivity of Quantitative Mobility Spectrum Analysis (QMSA) Technique
QMSA is a state-of-the-art analysis technique developed at UWA, and currently licensed to a US scientific equipment supplier, for characterising multiple hole and/or electron carrier species that often exist in modern semiconductor materials and devices. This project seeks to investigate theoretically the influence of sample’s non-uniformities (such as material composition, doping level, thickness) on the transport parameters extracted by QMSA.
B.2 Characterisation of Silicon-on-Insulator (SOI) Materials
In the present bulk-Si nanoelectronics technology, where individual transistors are already approaching the size comparable with silicon layer thickness (tens of nanometres), the size/thickness related issues lead to fundamental problems in the process of scaling devices. It is generally believed that further miniaturisation will be achieved through Silicon On Insulator (SOI) technology, which, in contrast to its predecessor, is based on silicon layers with thickness approaching less than ten nanometers, allowing further scaling without compromising the size/thickness ratio.
This project involves characterisation of electrical transport properties of state of the art SOI wafers, supplied by oversees vendors, using Hall Effect and Magnetoresistance techniques.
MERCURY CADMIUM TELLURIDE
The MRG has an established Molecular Beam Epitaxy (MBE) growth facility for mercury cadmium telluride (HgCdTe) semiconductor structures for high-performance infrared detectors. MBE, a state of the art technology for semiconductor crystal growth, allows growth of layers of different semiconductors, from as thin as a single atomic layer, to layers tens of microns thick. MBE technology is very important for fabrication and design of ultra-high performance electronics and optoelectronics devices using bandgap engineering. The Defence Science and Technology Organisation (DSTO) selected the Microelectronics Research Group to establish a university based MBE facility for the growth of mercury cadmium telluride (MCT) semiconductors, using equipment worth ~$3.5 million donated by DSTO.
B.3 How to Make Stable Semiconductor Materials
While mercury cadmium telluride is the best material to make infrared detectors, it also has many difficulties. One of these is that the surface of the semiconductor is very sensitive. To fix this problem, the surface is coated using another material (cadmium telluride). While this works, it is unclear why it works and if this is the optimum way of fixing the problem. This project will investigate the interface between the two materials to try and understand what is happening. This will be done using very simple semiconductor devices – capacitors and photoconductors. The capacitor (a metal-insulator-semiconductor or MIS capacitor) allows extraction of data related to charges trapped at the interface and how they are trapped. A photoconductor is a light sensitive resistor that can be used to measure rate at which electrons and holes are trapped at the surface. HgCdTe material used in this work is either grown in-house (using Molecular Beam Epitaxy) or purchased externally. In either case, to prove the device quality of the material photoconductors are an ideal test device.
B.4 How to Make Nano-scale pn Junctions in Mercury Cadmium Telluride
Making a pn junction diode in mercury cadmium telluride is the basis of the most sensitive infrared detector structures. The size of the pn junction directly relates to how sensitive the detector is (may be surprisingly, the smaller the size of the diode, the more sensitive the detector can be). We have developed a very simple technique that should allow us to make pn junctions diodes with areas less than 1μm×1μm (that is less than 10-6mm2, or less than around one hundredth the diameter of a hair). The problem is then, how to you characterise such small diodes or even make contact to them. In this project you will use a scanning laser microscope (SLM) to do this. The SLM can be used for a number of techniques including: transient lifetime, laser beam induced current (LBIC) spatial photoresponse.
· Transient lifetime measurements are used to measure the lifetime of carriers in a semiconductor. Carrier lifetime is one of the most important semiconductor parameters and has a significant effect on the performance of devices fabricated from semiconductors. Transient lifetime is measured by illuminating the semiconductor with a pulsed focussed laser, and measuring the decay time of the resulting electrical signal.
· The LBIC technique is being investigated as a non-destructive in-process testing tool for the characterisation of IR arrays. Ideally the LBIC tests will give information about individual photodiode performance, and the overall uniformity of the arrays. Projects in this area will investigate the correlation between LBIC signature and device performance.
· Spatial photoresponse uses a focussed laser to stimulate carriers in a photodetector device, enabling the local response of the material to be measured. By scanning the laser in a 2-dimensional space enables the uniformity of the detector active area to a quantitatively assessed.
These projects involve use of lasers, low-noise amplifiers and the measurement of extremely low signals. Once measurements are obtained various data analysis techniques are then employed determine device and material performance.
B.5 Characterisation of MBE Grown Material
Molecular Beam Epitaxy is the required semiconductor growth method for fabrication of complex multilayered device structures. The MRG runs an MBE growth facility that can grow HgCdTe. This project will look at the analysis of the grown semiconductor layers using a number of material characterisation techniques including Secondary Ion Mass Spectrometry (SIMS), LBIC, and Hall measurements and transient lifetime.
B.5.1. Characterisation of MBE grown MCT by x-ray diffraction
The X-ray diffraction facility at LaTrobe University in Melbourne has recently gone 'on-line'. Be the first to use this 'telepresence' system to make measurements on the sub-nanometer scale of the crystal structure of MCT samples grown at UWA. The results will be analysed to give information about strain and defect formation in the semiconductor layers.
B.5.2. Measurement of molecular fluxes in molecular beam epitaxy using cavity ring-down spectroscopy
This project is the start of a much larger project which aims to measure very low concentrations of gases in a semiconductor crystal growth chamber using optical absorption techniques. Cavity ring-down spectroscopy is a new ultra-sensitive laser absorption spectroscopy technique that can be used to detect gas concentrations to much less than one part per billion. The student will be involved in predicting the sensitivity of various cavity ring-down experiments and constructing models of the optical absorption spectra expected during crystal growth.
B.5.3. High precision multi-channel voltmeter/data acquisition system
High performance analogue to digital conversion (ADC) chips are now readily available at low cost, offering the possibility of constructing a high precision / low data rate voltmeter with computer interface at a lower cost than commercial systems. This project aims to create a multi-channel data acquisition system for monitoring several process variables during semiconductor crystal growth. The system will require a PC user interface (written in LabVIEW) to communicate with a microcontroller/ADC board and low-noise input electronics
B.6 Characterisation of Plasma Processed HgCdTe
Plasma processing via reactive ion etching (RIE) is the technique used by the MRG to convert p-type HgCdTe to n-type and thus form an n-p junction. This project will undertake characterisation of this converted region. The methods that will be used include Hall measurements and Secondary Ion Mass Spectrometry (SIMS).
III NITRIDE
III nitride (GaN, AIN, InN and alloys) semiconductor technology is relatively immature, with significant progress in this material system only having been achieved in the last 15 years or so. Despite the many inherent advantages of nitride-based materials, significant challenges still exist in the growth and fabrication of devices. Therefore there is much to be learned regarding both the fundamental material properties of and defects within the material. Such studies are critical in enabling nitride-based technology to reach its true potential.
The majority of the III nitride materials studied in the MRG are obtained as part of a long standing collaborative arrangement with the University of California at Santa Barbara. The MRG undertakes the detailed materials characterisation needed in the development of new device structures.
B.7 Optical Measurements of GaN Minority Carrier Properties
Measure an important but elusive property in nitride material. GaN material quality is directly related to its ability to emit light, which in turn is related to minority carrier lifetime. This project will use novel techniques that utilise photocurrent and photo-induced luminescence to investigate minority carrier properties in GaN material, and consequently use this information for improved materials and device performance.
B.8 Device Processing of GaN
Help develop state-of-the-art gallium nitride processing capabilities. GaN is a desirable material partly because of its high temperature stability and chemical inertness. However, these properties also make device fabrication difficult. This topic includes investigations into etched wafers and fabricated metal contacts, both challenging but vital processing steps.
B.9 Hall/QMSA of III-nitride Materials
Good transport properties (carrier concentration and mobility) of III-nitride materials are of vital importance for application of these materials into state-of-the-art devices. These projects will involve transport measurements using the powerful 12T magnet and then analysis of results using QMSA. Particular materials of interest include ion-implanted GaN, and InN.
POROUS SILICON
Porous silicon is a novel nano-material with the capability to perform as a mirror, waveguide, light emitting diode, photodetector, and sensor. Porous silicon is formed by the anodisation of crystalline silicon, and can be produced with a wide range of refractive indices, varying surface area, variable energy bandgap. Furthermore a variety of materials can be infiltrated into the nanopores, including polymers, biological species, and liquid crystals. Aside from optoelectronics, other applications include: photonic bandgap structures in micro-optics, solar cells for energy conversion, gas sensing for environmental monitoring, high etch selectivity for wafer technology, highly controllable etching parameters for micromachining, biosensors, and enzyme immobilization in biotechnology.
B.10 Development of Porous Silicon-based Devices for Optoelectronic Applications
This area of research is relatively new within the group and hence work in this area will concentrate on the development of a process for the fabrication of porous silicon and characterisation of the material. The ultimate aim is to produce devices for optoelectronics applications. Some key parameters of porous silicon are: porosity, porous silicon depth, optical properties, homogeneity. These parameters are to be measured as a function of the formation process parameters. This project will involve the investigation of techniques to produce uniform layers of porous silicon for optoelectronic device applications.
Porous silicon-based devices that are currently being developed within the group are: distributed Bragg reflectors (mirrors) for optical filters, and anti-reflection coatings for micro lenses.
B.11 Build a Sensor Based on Porous Silicon
Porous silicon is an advanced material which can be used for biological and gas sensing applications. This project explores the possibility to make a low cost optical sensor based on porous silicon. An array of light emitting diodes, each with a different wavelength will be reflected from the porous silicon surface and measured over time. The change is reflected signal level will provide an indication of the analyte being sensed. This project is perfect for mechatronics engineers. The project includes electronic and mechanical design. Skills to be developed include mechanical design, optical sensing, an understanding of porous silicon, and understanding of sensing technologies, signal processing, data collection and analysis.
B.12 Study of Stability of Porous Silicon
One ongoing issue with porous silicon is that the material is not stable when exposed to atmosphere, which leads to device characteristics changing over time. This project aims to implement a series of tests to determine if various treatments will render the material stable. Approaches for stabilising porous silicon include annealing and functionalisation of the surface. Accelerated aging tests will be performed on the material and tools such as reflectance measurements and FTIR will be used to assess the stability.
B.13 Measurement of Thermally-induced Stress and Its Effect on the Optical Properties of Porous Silicon
The thermal and optical properties of silicon are well known. However, when forming pSi, a significant portion of the silicon matrix is replaced with air (pores). If these pores are filled with different material (oxides or nitrides) the optical and mechanical properties of the films change. Since these films are used for the creation of optical (bio) sensors and micro-electro-mechanical devices, and understanding of these properties is extremely important. As part of this work, students will have access to and learn about a range of advance metrology tools such as Fourier Transform Infrared (FTIR) spectrometers, optical profilometers and optical characterization systems.
B14 Direct Laser Writing of Structures into Porous Silicon
PSi is extremely important for forming optical (bio) sensors and micro-electro-mechanical devices, however optical photolithography (used extensively in microelectronics) cannot be used on these films as the films are incompatible with the chemical used. Recently, we have developed a technique to make these films robust (passivating) in the presence of these chemical, but requires heating films rapidly to 600C ina nitrogen atmosphere. This project aims a using a focused laser beam onto the surface of the pSi to achieve the temperatures required in a very localised region, selectively passivating areas of the film. Subsequent exposure to a weak-base should remove all regions which were not exposed to the laser. Using a computer controlled XY stage, we intent to directly write features into the porous film.
C. ELECTRONIC/OPTIC SYSTEMS
(JM Dell, A Keating)
The projects in this area involve the design and production of electronic and optics systems that assist in characterising MRG devices or demonstrating the capabilities of MRG work.
C.1 Design of Automated Soil Analysis Instrumentation for Agriculture.
In agriculture, the cost of inputs to production (seed, water, fertilizers, insecticides, herbicides, etc) is rapidly increasing, and returns are increasingly tied to crop quality. The ability to be able to monitor soils and target where fertilizers, herbicides etc need to be applied, and where the highest quality produce is likely to be harvested is now essential information for farmers, but is so expensive to obtain that it can only be used on a limited scale. Projects in this area are examining the instrumentation required to be able to measure key soil parameters in real time using optical techniques including infrared analysis and laser light scatter, and electrical probe measurements. Specific projects include design of optical systems to measure infrared signatures of soil, implementation of laser scattering measurements to determine particle size, use of electronic and RF probing techniques to determine moisture content, and analysis of infrared signatures to extract soil properties. Applications include wheat, rice and other grain farming, and analysis of soils for vineyard production monitoring. These projects will be undertaken in cooperation with the School of Earth and Geographical Sciences and the School of Plant Biology.
C.2 Infrared Analysis of Breast Milk
Breast milk is recognised as the optimum nutritional source for new born infants. However, for premature babies, it is often essential to supplement breast milk in order that essential nutrients are included in the baby’s food. To determine if such supplements are needed, the mother’s breast milk must be analysed, requiring often significant sample volumes, which are then not available to the baby. This project, undertaken in collaboration with Biochemistry and Molecular Biology at UWA, is examining ways in which infrared spectroscopy, microfluidics and signal processing can be combined to obtain real time measurement of key nutrients in breast milk using very small sample volumes.
C.3 Design of a Sub-picofarad Capacitance Measurement System
To accurately control displacement in many MEMS devices, the capacitance between two parallel plates is measured. Because of the size of the devices, this capacitance is very small. This project will look at capacitance measurement techniques that can be implemented in analogue field programmable gate arrays. The initial designs will use a technique that called a “balanced-bridge,” but other techniques are possible. The skills required for this project are an interest in electronics design, an interest in implementation of a system, and some budgetary skills (the project will have a budget which is reasonably large but not infinite).
C.4 Design of a Position Control System for MEMS Tuneable Detectors
This project will look at implementation of a control system to accurately and precisely set the wavelength of a tuneable detector. It is an electronics design project, which will be implemented in a combination of analogue and digital field programmable gate arrays. The control system is notionally simple, generating a voltage that controls the separation between two plates. The capacitance between the plates will be used to sense the separation between the plates (it is this separation that controls the wavelength of the tuneable detector). The skills required for this project are an interest in electronics design, an interest in implementation of a system, and some budgetary skills (the project will have a budget which is reasonably large but not infinite).
C.5 An Automated Computer-controlled Gantry for Improving Porous Silicon Fabrication
The aim of this project is to design and build an automated computer controlled gantry for a multi-bath porous silicon growth system. Background: Porous silicon is a novel material for many opto-electronics applications. The Microelectronics Research Group is currently investigating growing porous silicon using a multibath method. To be able to do this safely and in an automated fashion a mechatronic gantry to move the porous-silicon growth cell between the baths is needed. The gantry will need to be approximately 600-800 mm wide and 400-600 mm tall. It will have a crane on the top rail controlled by stepper motors which can accurately move the porous-silicon growth cell between up to four baths. The baths themselves are 120x180mm and will be located on a raised platform. The system will be controlled using a computer through a PIC micro-controller and an RS232 interface. The student undertaking this project will gain basic knowledge of the porous silicon growth process and how the system is aiming to improve on current limitations. The project will involve skills in mechanical and electronic design, and as such will ideally suit a mechatronics engineer although mechanical and electrical engineers are encouraged to consider this project.
C.6 Build an Ellipsometer to Measure Scattering in Porous Silicon
To understand the characteristics of porous silicon, an advanced material used for sensors, detailed optical characterization if required. Current methods used are inadequate to accurately determine the porosities of the film and the roughness of the porous silicon/silicon interface. This project is perfect for mechatronics engineers. The student will gain an understanding of porous silicon and it’s applications, design, build, test and analyse an ellipsometer to characterize porous silicon. The ellipsometer requires high precision 2-axis rotational control of a optical beam and the sample. Skills in signal processing, mechanical design and control will be developed as part of the project.
C.7 Build a Micro-gram Scale for Gravimetric Measurements of Porosity in Porous Silicon
To find the porosity (density of holes) in porous silicon it is required to measure the weight of the silicon before and after forming pores (porosification). However, the expected change in weight is in the order of 10-4 grams, requiring a scale with an accuracy of at least 10-times less than this value. Commercial scales often compromise between range of measurement and accuracy. However, the largest weight we expect to measure is the bare silicon, which comes to around 1.4 grams, requiring a dynamic range of only 105. This project aims to build, characterize and calibrate a highly accurate scale for porous silicon. The student will subsequently form porous silicon samples and determine the porosity verse anodization current. This project is perfect for mechatronics engineers. The student will gain an understanding of porous silicon and its applications, design, build, test and analyse a highly accurate scale and address the issues associated with the scale accuracy including drift due to temperature, humidity and air movements. Skills in signal processing, mechanical design and control will be developed as part of the project.
D. ATMOSPHERIC PROPAGATION
(N Fowkes, BD Nener)
The ultimate performance of an EO System is determined by the atmosphere. The atmosphere can degrade the signal through scattering and absorption by aerosols, background radiation, scintillation and refraction. Projects in this area are both theoretical and/or involve experimental work. The experimental work is at sites like Rottnest measuring atmospheric parameters important to EO propagation and involves the design and installation of the instruments, and the analysis and modelling of atmospheric data and effects. The theoretical work involves mathematical and numerical modelling of atmospheric effects relevant to EO systems, particularly refraction and scintillation.
Current work is funded by the Australian Department of Defence and Tenix Defence Systems Ltd (an Australian owned defence contractor). The effort is in collaboration with the UWA Department of Mathematics and Statistics; the Remote Sensing and Satellite Research Group (RSSRG) of the Physics Department of the Curtin University of Technology; CIMSS, Space Science and Engineering Center, University of Wisconsin, Madison, Wisconsin, USA, and the US Navy Space and Naval Warfare Center (SPAWAR), San Diego, USA.
D.1 Refractive Index Change in Atmosphere
Modelling of the effects on light and microwave propagation of refractive index changes due to temperature gradients in the atmosphere over the ocean; modelling of mirages and other image distortions of objects seen at large distances; scintillation.
E. INTEGRATED CIRCUIT DESIGN (Associate Professor Farid Boussaid)
E.1 Camera-on-chip
|
The current trend in Digital Imaging Technology is towards building camera-on-a-chip imaging systems, i.e., CMOS imagers. The fully integrated product results in significant manufacturing cost savings, reduced system size, but also in lower power consumption. The unique concept of CMOS imagers offers the opportunity to integrate photo-sensing array and signal processing circuitry on a single silicon chip, enabling the development of a new generation of smart mobile imaging systems. Half the size of a small postage stamp, a CMOS imager chip can even be swallowed (pill-camera) to transmit images from inside the body. Besides biomedical, CMOS imagers have numerous commercial applications in cell phones, PC notebooks or any application for which a “micro-camera” can be requested. |
|
|
|
Microphotograph of a fabricated CMOS imager (3.5×3.5mm2) |
Proposed final year projects will involve building such a camera, and optimize its performance in terms of dynamic range, resolution and/or power consumption. During the project, you will further develop your analog/digital electronic design skills.
E.2 Electronic nose
Sniffing-dogs are able to detect thousands of chemicals with high sensitivity and selectivity using only biological components. These nasal powerhouses have been successfully used to search for pipeline leaks, drugs, or explosives. You will develop a biologically inspired Electronic Nose (or ENose for short), that mimics the organization and neural processing of the olfactory bulb. The Enose will comprise a chemical sensor array and a gas recognition engine, integrated on a single chip. Projects offer an opportunity to discover and apply neuroscience principles into made-made engineering systems. Projects will be tailored around your interests, whether neuroscience and/or integrated circuit design.
Microphotograph of a fabricated electronic nose
E.3 UWA Unmanned Aerial Vehicle (UAV
We seek to develop, design and manufacture a UWA-made UAV (Unmanned Aerial Vehicle). UAVs are man-made flying vehicles capable of operating without a person on board. UAVs come in a large variety of sizes and shapes and applications. This project will focus on the ‘miniature’ UAV category, which is defined as having a maximum take-off weight of 30Kg, maximum flight time of 2 hours and a maximum altitude of 300 meters. This category represents a good trade-off between size, complexity and cost when compared to larger UAVs. Mini-UAVs are large enough to carry useful payloads such as digital cameras, sensors and other equipment. They are also small enough that they can be built relatively cheaply and do not come with the strict regulation requirements for operating and testing larger aircrafts.
The core components of a UAV are: the airframe, the propulsion system, the avionics, the radio data link, the base-station and the payload. Given that the UAV project has just started, help is sought at all levels and disciplines.
