Low Temperature Silicon Film Deposition By Pulsed Cathodic Arc Process for Microsystem Technology  Researchers at Michigan Tech demonstrated for the first time the deposition of doped silicon films by pulsed cathodic vacuum arc techniques. The development of silicon thin films is attractive for many applications in the field of microelectronics and micromechanics such as thin film transistors, solar cells devices, and structural elements in microelectromechanical system (MEMS). The production of MEMS device quality silicon film materials at low temperature would further enable the integration of microsystems with microelectronics. To meet a growing variety of device technology requirements, attention is given to the processing methods to control the materials' growth and properties. As a technique for high quality film growth, cathodic vacuum arc deposition is characterized by low deposition temperature, high deposition rate, relatively low operational cost and high-energy process capabilities due to the nature of arc plasma discharge.
The direct current (D.C.) and pulsed current vacuum arc comprise two approaches implemented for film deposition. Compared with D.C. arc, pulsed arc has the advantages of higher ion energies and higher deposition rate as well as the reduction of macro droplets intrinsically associated with the cathodic arc process. However, two main issues limit the utilization of vacuum arc on silicon material. One is that the arc cannot be initiated on the intrinsic silicon unless it is heavily doped or is heated to increase the intrinsic electric conductivity substantially. The other problem with silicon is low thermal conductivity compared with most metals. The local heating at cathode spots and the resulting thermal shock can cause the silicon target to crack. Previous reports of cathodic vacuum arc on silicon film deposition were focused on the D.C. arc operation only. Pulsed technology is more appropriate for silicon cathodic arc deposition.
Compared with the D.C. arc process, more uniform target erosion and better control of the silicon spots were achieved by adjusting the pulsed arc current parameters. The deposition rate was high at 0.2nm/A.s in comparison with other available technologies. The microstructure of the films was dense with polycrystalline macro droplets embedded in an amorphous silicon matrix. |
Magneto-Photonic Crystal Isolators This technology allows for the development and fabrication of an ultra-short optical isolator that can be integrated onto a microchip. Isolators created with this technology could be used in integrated photonic circuits and are smaller and more inexpensive than isolators fabricated by traditional means. |
MEMS Center in Wireless Integrated Microsystems A multi-university National Engineering Research Center in Wireless Integrated Microsystems funded by the National Science Foundation gives MTU a strong base for microtechnology research. Among its first projects, the center will design a next generation cochlear implant for which MTU will design and build a |
Magnetic Photonic Crystals Researchers are in the process of developing important materials research solutions that will enable the application of thin film magnetic photonic crystals to high performance electro-optical devices. Of great interest is a process that allows characterization and measurement of properties of novel materials that can simultaneously show piezoelectric properties, and change their index of refraction. These materials are used as [photonic crystals], materials that selectively filter frequencies of light and are tunable with an electric field. |
Embedded systems and Artificial Intelligence Derived Biosensor Devices  This is application-driven research focused on the use of artificial intelligence and embedded systems in biosensors and imaging devices. One of the technologies that is being developed involves a device that traps and kills HIV infected cells. The device conceivably would be implanted into the lymph system and proactively recruit infected cells. Additionally, research is focused on a sensor to map the progression of brain cancer using 3-D mathematical modeling and an embedded systems approach. While these are early stage technologies, the architecture that enables functionality of the sensors involves the generation of a circuit without using a microprocessor. The research has yielded a way to use JAVA to create the circuit. This concept could have the potential to be used in a number of different applications, including wide use in the biosensor field. |
Integrated Photonics and Materials Integration Laboratory The equipment in the laboratory serves the fabrication, testing and analysis of photonic and piezoelectric structures, materials and film-based devices. Research in integrated photonics centers on the use of magneto-optic and electro-optic materials. Recent work has centered on the development and fabrication of magnetic photonic crystals. A second thrust involves the development and fabrication of optical and microelectromechanical systems (MEMS) based on novel highly efficient piezoelectric films.
Tools consist of an rf magnetron sputtering system for the fabrication of magneto-optic films; an electron-beam writing system housed in a JEOL 6400 SEM and a Hitachi Focused Ion Beam (FIB) System for nano-patterning of photonic structures, both housed in the Applied Chemical and Morphological Analysis Laboratory; a metal evaporator for the deposition of electrodes; a micro-manipulator; a prism-coupler for the study of refractive indices and film thickness; an optical testing laboratory for the analysis of waveguide devices that includes HP and Ando infrared tunable laser sources. |
Atomic and Molecular Laser Spectroscopy Laboratory The objective of the research in the atomic and molecular laser spectroscopy laboratory is to gain knowledge about the basic properties of ions and neutral atoms and molecules, with a particular emphasis on the properties of molecules in electrical discharges.
A tunable CW diode laser of bandwidth better than 1 MHz and stability on the order of 100 MHz per hour was designed and built in the laboratory. Additional equipment includes a high power, high resolution tunable dye pulsed laser pumped by the third harmonic of an Nd-YAG laser along, with electronics capable of processing events as fast as half a nanosecond and detecting a single photon. |
Multi-Scale Technologies Institute (MuSTI) Multi-scale technologies are those that bring together functional elements to form systems where the relative size of components within the system spans from the nano through the micro and into the macro domain. The systems-focus of MuSTI emphasizes the challenges associated with integrating technologies that have relative feature sizes orders of magnitude apart and operating characteristics that are size dependent. This presents many problems that must be addressed by interdisciplinary teams of researchers using specialized equipment. Research focuses on engineered systems and components such as nanoelectronics, nanosensors and systems, and associated materials. |
Center for Nanomaterials Research The Center for Nanomaterials Research is an interim center at Michigan Tech leading to a more comprehensive center focusing on the science and applications of technologies across many orders of dimensional magnitude and integrating nanotechnologies with microtechnologies and conventional systems. The interdisciplinary research can be summarized in three areas. The first is the modeling and development of room-temperature single electron transistors coupled with proteins to form nanosensors and electronics for sensing applications. These components are based on quantum effects that dominate at component sizes of approximately 10 nanometers or less. Biological proteins offer many sensing advantages including narrowly defined sensitivity, no power consumption, and self-assembly. The second area is the modeling and development of magnetic nanophotonic devices for optical communications and navigation systems. These devices literally grow and shrink under the influence of a magnetic field changing the transmission properties of light. These are efficient filters and modulators that can operate over a wide spectrum in a single device. The third area is the physical and functional integration of these devices with microscale and conventional systems through interconnection technologies. The electrical and mechanical behavior of connections that operate at both the nanoscale and microscale will be systematically evaluated. Component feature sizes may be as small as several nanometers in devices with dimensions of micrometers driving a system with dimensions of millimeters. The thrust of the center is to develop technologies that exploit the advantages of small size and low power of nanoscale components and yet retain the functionality of conventional-sized systems. |
Contact Angles on Materials with Heterogeneous Surfaces This research program is an exploration of the interaction of fluids with heterogeneous solid surfaces are particularly important in material surface-based industrial processes such as printing, patterning, fabrication of MEMS devices, separation of plastics, de-inking flotation, and others. Because these interactions depend on the nature of the heterogeneity, its size, morphology, and distribution, a comprehensive study of the interaction between fluids and heterogeneous surfaces is an important advance. The results are being used to test available theories of wetting phenomena; experiments involve real-world heterogeneous materials and “well defined” heterogeneous surfaces composed of adsorbed and self-assembled organic layers of varying functionality, structure, and density. Both atomic force microscopy and contact angle measurement technique are used in examination of interactions of fluids of varying polarity with heterogeneous surfaces. |
Using Atomic Force Microscopy (AFM) to Analyze Surface Energy of Pull-off (Adhesion) Forces Atomic force microscopy (AFM) is capable of characterizing solid surfaces at the microscopic and sub-microscopic scales. As demonstrated in several laboratories in recent years, it can also be used to determine the surface tension of solids based on adhesion (pull-off) force measurements. Before AFM force measurements can become an accepted technique for particle-substrate adhesion characterization, individual problems causing irreproducibility of the measurement must be resolved. This is particularly important in the measurement of pull-off forces in very complex geometry systems that are of importance to the industry. For example, this research program has resulted in measures of the adhesion forces between pharmaceutical particles with irregular geometry and polymeric surfaces of varying roughness in a gas of controlled humidity level. |
Heteroepitaxial growth on compliant substrates This program of research is focused on the fabrication, characterization, and properties of nanoscale layered structures. Additional concentrations include the integration of dissimilar materials through wafer bonding and the relationship between structural, optical and electronic properties of heterostructures. |
Magneto-Electric Nanostructures for Novel Microwave The objective of this collaborative research is to fabricate and study the magneto-electric interactions in novel one-dimensional ferromagnetic-ferroelectric nanostructures, and to exploit them for innovative device applications. The program is motivated by theoretical models that suggest much stronger interactions in such nanostructure geometries than in standard thin films and laminate structures. The approach is to synthesize nanowire and nanotube composites consisting of ferroelectric materials, such as lead zirconium titanante or barium titanate, with ferrimagnetic nickel- or cobalt ferrite.
A comprehensive research program is planned consisting of the following components: sample fabrication, structural characterization, magneto-electric interaction studies spanning a wide frequency range, device studies, and theoretical modeling. Efforts will focus on the creation of novel nanostructures using innovative processing methods and examine their use for a new class of microwave devices that are both electric and magnetic field tunable. At the University of Alabama, the PI will lead the sample fabrication, structural characterization and device fabrication efforts; while the physical property measurements, theoretical studies and device applications will be led by the PI at Oakland University.
The efforts will bring together a multidisciplinary team of investigators that will make significant contributions to scientific knowledge, education outreach and infrastructure, and potentially lead to a host of next-generation devices for the national defense and consumer electronics. The program will provide support for graduate and undergraduate students, including underrepresented minorities, and contribute to their broad interdisciplinary training. Project personnel will collaborate with local schools to facilitate participation by high school students in research. |
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