Micro- and Nano-Composite Ceramics
New Methods for the Synthesis of Silicon Carbide Based Micro- and Nano-Composite Ceramics
Tech Area / Field
- MAN-MAT/Engineering Materials/Manufacturing Technology
- INF-ELE/Microelectronics and Optoelectronics/Information and Communications
3 Approved without Funding
National Polytechnical University of Armenia, Armenia, Yerevan
- Institute of Electronic Structure & Laser, Greece, Heraklione\nEricsson AB / Microwave and High Speed Electronics Research Centre, Sweden, Molndal\nChalmers University of Technology / Department of Microelectronics, Sweden, Göteborg\nCalifornia State University, Bakersfield, USA, CA, Bakersfield\nRDL Equipment, USA, AZ, Gilbert\nFIT - Ceramics, Germany, Miesbach
Project summaryThe main objective of the proposed Project is development of new cost effective processing methods for fabrication of nano-composite ceramics. More specifically two cost effective methods - Chemical Frontal Polymerization (CFP) and High-temperature Self-propagating Synthesis (SHS) methods will be developed and used for the synthesis of nano-composites of different polytypes of SiC (SiC/SiC, SiC/Si, SiC/Ge, SiC /Me). Further objectives of the Project include:
- Analysis of the primary mechanisms of formation of the nano-composites and determination of the processing conditions for the fabrication nano-composites.
- Investigate (experimentally) the quantum-mechanical and physical processes, the mechanisms of electrical and thermal conductivities, and other sensorial (gas, optical, thermal radiation etc.) properties of the synthesized nano-composites.
- Investigate the influence of the external, as well as the processing conditions and internal micro and nanostructure (microstructure variation, surface condition, interface behavior, grain size, the presence of insulators between the grains, the presence of trap concentration at the grain boundaries and their thickness etc.) on the macroscopic parameters of the nano-ceramics.
- Validation of the results via development of temperature, pressure, chemical, biological etc. sensors (depending on the properties of nano-ceramics). The validation demonstrators will be facilitated by microwave electrodes and targeted at applications in Radio Frequency Tags (RFID) and wireless sensor (ZigBee) systems.
The actual tasks include:
- To study and establish the combustion law for the multi-component systems, to solve the problems associated with the control of combustion temperature, speed of propagation front and to control the conversion degree.
- The investigation of the physical-chemical conversion mechanisms and the influence of technological processes on the electrical and sensorial properties of synthesized composite structure also will be very important during this project.
- Based on the obtained results, it is planned to develop a SHS technological continuous operating system for fabrication of semiconductor ceramics and composite nanostructures.
The proposed Project is dedicated to synthesis of different SiC/SiC SiC/Ge, SiC/Si, SiC/Me nano-composite heterostructures and thin films, SiC matrix based nanoceramic microsensors (gas, optical, thermal radiation etc.) using new methods. We plan investigation and determination of the primary mechanism and processing conditions of the synthesis and fabrication, theoretical and experimental investigations of the static and dynamic current-voltage, capacitance-voltage and other sensorial properties of above mentioned structures. The effects of processing conditions on the micro-structure, surface state and interface states will be studied out experimentally and correlated with the electrical, optical responses and other sensorial properties. Similar investigation will be carried out using microsensors based on nanocomposite thin films and heterostructures.
The results of these experiments will be compared with our theoretical models and will enable interpretation of the main physical phenomena (for example formation of NDR and quantum size effects) and mechanisms of current flow in nano-ceramics and heterostructures. In some cases those dependencies and data need additional physical explanation. The current transport mechanisms and contact properties of above mentioned nanostructured ceramics, and heterostructures will be measured and estimated and performed using a modified four point probe method, as well as using non-destructive (e.g. contactless microwave) and contact less and other testing and analysing methods.
Experimental investigations of the sensorial properties of nanoceramics, heterostructures, and microsensors based on them will be carried out in temperature range 77-1200 K. The current-voltage (I-V) measurements in the forward and reverse directions will be carried out by using a Precision Semiconductor Parameter Analyser. The capacitance-voltage (C-V), conductance-voltage (G-V) measurements will be carried out using a bridge capacitance meter with a probe frequency of 1MHz. Using the results of C-V measurements the doping concentration Schottky barrier height and interface trap affect on electrical and sensorial characteristics will be estimated.
Electrooptical measuring method will be applied to characterize the properties of nanostructured ceramics and heterostructures. Especially for the size-dependent electroabsorptive properties of absorption spectra of samples will be carried out using white-light spectrometer. The X-ray diffraction method will be carried out to analyze the phase formation, surface and structural properties of nanostructured ceramics and heterostructures. For the structural, chemical and morphology investigations of the forming samples the Scanning Electron Microscopy methods will be used. Contactless microwave (dielectric) characterisation of the samples, in the frequency range up to 50 GHz, will be carried out by our collaborator at Chalmers University of Technology, Sweden.
The utilization of new effects and phenomena (e.g. quantum-size effects) in semiconductor micro- and nano-structures evidently require development of new and cost effective methods of the synthesis and processing conditions, including their physical, mathematical models and experimental characterization methods. To solve these problems it is necessary:
- to design new methods (particularly, CFP and SHS methods) of synthesis and fabrication of nanostructural ceramics and heterostructural thin films
- to analyze and model their synthesis conditions;
- to investigate (experimentally) the quantum-mechanical and physical processes, the mechanisms of electrical and thermal conductivities, optical and other sensorial properties;
- to investigate the influence of external, as well as the technological factors and internal structural parameters (microstructure, surface/interface conditions, grain size, the presence of insulators between the grains, the presence of trap at the grain boundaries etc.) on the electrical/dielectric properties of nanocomposites and devices based on them;
- to make theoretical and experimental analysis of the results and make recommendations for the optimization of the processing conditions of the nanaoceramics and devices based on tem.
In the experimental field we have many interesting and important dependencies and data concerning Si/Ge, Si/C and of various monocrystals SiC/metal structures, as well as SiC ceramic microsensor properties. Such ceramic structures were been fabricated by conventional ceramic processing as well as by above mentioned advanced methods taking into account the initial components ratio, various technological factors and regimes. The investigations carried out on fabricated samples show, that such ceramic structures exhibit interesting current-voltage characteristics behavior. Ohmic and nonlinear behaviors on the characteristics have been observed dependent on synthesis conditions. The typical current-voltage curve for SiC/Ge samples has shown an evident nonlinearity similar to ordinary diode characteristics. Moreover, the fabricating samples have exhibited sensorial behavior. Particularly SiC/Ge structures show high moisture and optical sensitivity. For some Si/Ge samples, fabricated using certain processing conditions, small current-steps was observed on current-voltage characteristics. The interpretation and analysis will help to uncover the physics (mechanism) behind the current-steps and model the current transport.
Participants of the Project have long-year experience in the fields of synthesis of different ferrites and other ceramic structures (Mg0.5-xMnxZn0.5Fe2O4, MnXZn1-XFe2O4,
Ni0.46Zn0.42Cu0.12Fe2O4, LaNi1-xFexO3, La1-xSrxMnO3, LaCr1-xMgxO3, LaxSr1-xCrO3), and Polymer-Ceramic Compositions, as well as theoretical and experimental investigations of SiC microwave/millimeter wave device characteristics. More than 100 papers in the proposed research field have been published by group in leading international and Soviet Journals.
Foreign collaborators may participate in fabrication of SiC nanostructured ceramics and heterostructures, as well as in the investigation of the electrical, dielectric/optical and other sensorial properties of SiC structures. The Microwave and High Speed Electronics Research Center of Ericsson AB, Moelndal, Sweden, plans:
- to make contactless measurements of the dielectric properties of the nanoceramics in the frequency range up to 50 GHz, including some sensorial properties, such as the effects of optical illumination (UV, visible, IR), humidity, temperature, gases etc. on the dielectric properties;
- consider the possibilities of integration of the sensors (gas, temperature, UV, IR etc.), developed in the project, in mobile phones and radio links units.
The role of foreign collaborators is also to discuss the problems and to exchange information, obtained during the implementation process of the Project, to take part in scientific seminars and conferences, organized by the executor. They may also assist the commercialization of the obtained results and their advance to the market.
Realization of the Project will make it possible to solve a set of problems, which correspond to the purposes of ISTC:
- reorientation of high-qualified scientific stuff, engineers and technical workers, being previously working in the sphere of armament, to solving peace problems;
- provision of scientists with an alternative peaceful job;
- further integration of scientists, working in the sphere of armament, with the international society of scientists; there will be developed traditional cooperation with the organizations and universities of CIS;
- development of science-consuming technologies in Armenia; etc.