Silicon carbide based nanostructures
The Syntheses, Fabrication and Investigation of SiC Based Nanostructures
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
- FIT - Ceramics, Germany, Miesbach\nUniversity of Trento / Department of Physics, Italy, Trento\nAgilent Technologies Inc., USA, CA, Santa Clara\nCEA / DSM / DRECAM/CEN Saclay, France, Saclay\nChalmers University of Technology / Department of Microelectronics, Sweden, Göteborg\nFachhochshule Aachen, Germany, Jülich\nEricsson AB / Microwave and High Speed Electronics Research Centre, Sweden, Molndal\nLEDA Design, Inc., USA, TX, Plano\nInstitute of Electronic Structure & Laser, Greece, Heraklione\nCalifornia State University, Bakersfield, USA, CA, Bakersfield\nNational Technical University of Athens, Greece, Athens\nIMAI & Co., Ltd., Japan, Tokyo
Project summarySubmitted proposal is revised version of Project A-1139, which includes all the comments and remarks of European Union, made in 34th ISTC Project Funding Session. The proposal includes detailed description of state-of-art problems, the results of comparison with recent progresses, more precision grounds for the Project issues as well as possible ways of their solution. Forms and fields of cooperation with foreign collaborators, including two new European industrial collaborators (Ericsson AB and FIT Ceramics), are defined concretely in the improved version of the Project as well.
Modern microelectronics has entered into a new phase of development – nanotechnological.
In most cases, micro- and nanotechnology go hand in hand: nanotechnology devices need integration into a microtechnology environment working as a linkage to the macroscopic world, whereas microsystems benefit from novel functionality provided by nanotechnology. This new area is concerned with materials and systems whose structures and components are exhibit novel and significantly improved physical, chemical and biological properties, phenomena and processes due to their nanoscale size.
Properties such as high breakdown electric field strength, reasonable electron mobility, wide bandgap, high thermal conductivity, high electron saturation velocity, high radiation stability make silicon carbide (SiC) an attractive candidate for fabricating high temperature, high frequency and high power electronic devices especially for applications involving elevated temperature operation and/or harsh environment. For this reason intensive researches are underway to be performed on SiC-based high power switch diodes, bipolar and unipolar transistors, optical and gas sensors, devices based on nano- scale structures, heterojunctions, ultraviolet detectors, and microwave devices. They are in the stage of lab investigation and need further improvement.
Other interesting quantum structures are Si or Ge nanocrystallites embedded in SiC. They can be fabricated by means of MBE or ion implantation with subsequent annealing. Investigations carried out in last years shown that it is now possible to manufacture such nanostructures in SiC crystals. Nanostructures are suggested to offer a new degree of freedom to tailor the electrical, optical and sensorial properties of SiC.
The formation of new quantum size effects requires to develop new technological methods and regimes of fabrication. In contrast to well-known methods of growth SiC (CVD, HTCVD, Lely Method, Sublimation Sandwich Method, Modified Lely Method or PVT, Advanced M-Lely Method) and fabrication of SiC based micro-, nanostructures and devices (LPE, MBE, ion implantation, etc) we planned to use new methods, as well, particularly the chemical frontal polymerization (CFP) and high-temperature self-propagating synthesis (SHS) methods for the formation of the above mentioned nanoceramics and nanocomposite thin films.
The CFP permits to avoid agglomeration of nano-particles during the thermal wave propagation and allows uniform distribution of incompatible components in polymer matrix. Our preliminary results shown that the high-frequency acoustic fields and the use of various surfactants allow having a uniform distribution of the nano-components in the initial reaction media, stabilizing obtained state and preparing polymer nanо-composites with uniform distribution of nanо-partiсles in the matrix.
Recently together with the well known ferrite materials, the SiC and TiC are produced by SHS or combustion synthesis methods. Because of high-efficiency, simplicity, low energy consumption and much lower production of pollutants, the synthesis proceeding under the combustion mode founds wide application. High temperatures developed in a combustion wave provide the fullness of conversion of initial materials to the final high quality products with the minimal impurities containing due to so called self-purification processes. Moreover, high velocity of processes leads to smaller synthesis times. By variation of parameters of initial components of mixture and the condition of combustion, it is possible to form products with given chemical and phase composition as well as with certain structures and properties. Our previous experimental investigations have shown that using the oxygen as an oxidant and the carbon as a fuel, provide the values of combustion temperatures and wave front propagation velocities in the 1400-1800 C and (1-4) mm/s, respectively.
The Project is devoted to the theoretical and experimental investigations of the SiC nanostructured ceramics, heterostructures and nanocomposite thin films, as well as to the determination of the primary mechanism and technological regimes of their formation and manufacture. The experimental investigations of the influence of technological and thermal processes, microstructural variation, surface condition, interface behavior on the electrical, optical and other sensorial properties of different SiC nanoceramic microsensors (gas, optical, thermal radiation etc.) and SiC/SiC SiC/Ge, SiC/Si, SiC/Me nanocomposite thin films and heterostructures will be carried out. Experimental measurements will be carried out for the above-mentioned SiC nanoceramic and quantum nanostructure thin films. Dependencies of their electrical (sensorial) properties on temperature (from77 up to 1200 K), sizes, surface and interface conditions, and other technological and chemical parameters will be measured.
Now we have many interesting and important dependencies and data of various semiconductors and metals in SiC matrix, as well as samples of SiC/Si, SiC/Ge, Si/Ge composite ceramics fabricated by means of SHS and CFP methods, which are require fundamental studies and characterization.
The Project is devoted also to theoretical and experimental investigation of the static current-voltage, dynamic and microwave characteristics of the above mentioned nanostructured ceramics and heterostructures. The analysis permits us to assume that our theoretical investigations will be useful and can explain the main physical phenomena and mechanisms of formation of negative dynamic resistance and quantum size effects in the transit-time and quantum-well SiC - based devices. In some cases these dependencies and data need additional physical explanation.
Therefore, the formation of new quantum-size effects and the change of their role require evidently to develop their physical, mathematical, structural-technological models of design and characterization.
To solve these problems it is necessary:
- to design new methods of formation and fabrication of nanostructural ceramics and heterostructural thin films,
- to analyze and model their technological processes and regimes;
- 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, technological factors and internal structural parameters (microstructural variation, surface condition, interface behavior, grain size, the presence of insulators between grains, the presence of trap concentration at the grain boundary dielectric layers and their thickness etc.) on the output characteristics of the devices;
- on the basis of the above mentioned theoretical and experimental results it will be easy and useful to manufacture a new class of high-speed, low-power, low- noise and high sensitive nanostructural ceramics, heterostructures and devices.
The current-voltage (I-V) measurements in the forward and reverse directions will be carried out 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 the electrical and sensorial characteristics will be estimated.
Electrooptical measurement methods will be applied to characterize properties of nanostructured ceramics and heterostructures. Especially for the measurements of size-dependent electroabsorptive properties of absorption spectra of the samples, an optical spectrometer will be use. The X-ray diffraction methods 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, Cathodoluminescence (surface mapping and spectroscopy), IR absorption/reflection Spectroscopy, X-ray Topography and Optical Microscopy methods will be used.
The participants of the Project are quite experienced in the field of theoretical and experimental investigations of SiC device characteristics and development of superconducting microwave/millimeter wave and infrared devices and systems. Qualification level of the SEUA specialists involved in the Project is rather high: 7 are three Doctors of Technology or Physics and Mathematics (including 5 Professors) and 5 Candidates, as well as many high qualification engineers.
Foreign collaborators may participate in fabrication of SiC nanostructured ceramics and heterostructures, as well as in the investigation of electrical, optical and other sensorial properties of SiC structures. They may also assist the commercialization of the obtained results and their advance to the market. 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.
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