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Published in Philip A. Laplante, Comprehensive Dictionary of Electrical Engineering, 2018
syntax syntax the part of a formal definition of a language that specifies legal combinations of symbols that make up statements in the language. synthesis filter a bank of filters that recombines the components decomposed by analysis filters from different frequency bands. synthesizer a software program that creates GDS2 data from a hardware description language specification such as VHDL or Verilog. synthetic aperture radar (SAR) a technique for overcoming the need for large antennas on side-looking airborne radar (SLAR) systems. The effect of a large antenna is synthesized by using Doppler shifts to classify the return signals, generating a very small effective beamwidth. The process is quite similar to that of holography, since the amplitude and frequency of the signals is recorded over time. synthetic diamond diamond grown artificially, usually as a film, for industrial purposes such as hardness, thermal conductivity, or optical properties. system a physical process or device that transforms an input signal to an output signal. For example, the following figure describes a system consisting of a RC circuit with an input of voltage, and an output of measured voltage across the capacitor:
Elemental Semiconductors
Published in Lev I. Berger, Semiconductor Materials, 2020
Carbon basically exists in two allotrope modifications: hexagonal graphite and tetragonal diamond. The p-T diagram of carbon as was presented by Bundy3.85 is shown in Figure 3.5. From the diagram, it is clear that synthetic diamond may be produced by metallurgical methods only at very high pressures and temperatures which technically allow growth of relatively small crystals. By now and apparently in the foreseeable future, the cost of synthetic gem-quality diamonds is substantially higher than that of native diamonds, and many physical parameters of natural diamonds important for their applications in electronic and optical devices are superior to those of synthetic diamonds.
Inorganic Polymers
Published in Charles E. Carraher, Carraher's Polymer Chemistry, 2017
The majority of diamonds (nongem) are now man-made. Most of the synthetic diamonds are no larger than a grain of common sand. The major use of synthetic diamonds is as industrial shaping and cutting agents to cut, grind, and bore (drill). By 1970, General Electric was manufacturing diamonds of gem quality and size through compressing pure carbon under extreme pressure and heat. It was found that the addition of small amounts of boron to diamonds causes them to become semiconductors. Today, such doped diamonds are used to make transistors.
Research on controllable ozone oxidation on diamond surface
Published in Functional Diamond, 2022
Tao Qiu, Meihua Liu, Tangbangguo Zhou, Xu Lin, Bin Xu
Since natural diamonds are extremely scarce, synthetic diamonds produced with high temperature and pressure are used as a substitute. Carbon atoms on the synthetic diamond surfaces frequently integrate with atoms of other elements to compose different surface terminations, due to the influence of diamond production processes (such as CVD, etc.). According to the different chemical states of diamond surface, diamond can be roughly divided into two types: C–H bond terminations (called hydrogen terminations) and C–O bond terminations (called oxygen terminations). Typically, diamond films end in C–H bonds, while diamond particles end in C–O bonds. The diamond surface ending with C–O bond usually contains hydroxyl (–OH), carboxyl (–COOH), bridge oxygen (C–O–C), carbonyl (C = O) and so on [2–4]. The physical and chemical properties of diamonds are greatly affected by them [5].
Tuning diamond electronic properties for functional device applications
Published in Functional Diamond, 2022
Anliang Lu, Limin Yang, Chaoqun Dang, Heyi Wang, Yang Zhang, Xiaocui Li, Hongti Zhang, Yang Lu
As a material with excellent mechanical and functional properties, diamond is greatly needed in a wide range of fields. The high cost of natural diamond pushes forward the research of synthetic diamond. Diamond can be divided into single crystal diamond (SCD) and polycrystalline diamond (PCD). PCD has higher concentration of defects comparing to SCD due to the presence of grain boundary and the electrical properties of devices made by PCD are significantly limited as a result [15]. Therefore, if we want to exploit diamond’s potential as electronic and optical devices (UV/radiation detector, field-effect transistor, diode, etc.), SCD is a better choice than PCD. In the following part of this review, all the diamonds we talk about are SCDs if there is no specific explanation.
Application of high-thermal-conductivity diamond for space phased array antenna
Published in Functional Diamond, 2022
Wei Lu, Jin Li, Jianyin Miao, Liangxian Chen, Junjun Wei, Jinlong Liu, Chengming Li
Diamond is the substance with the closest arrangement of atoms in nature, and it possesses outstanding thermal properties. In particular, the ultra-high thermal conductivity is one of the many extraordinary properties of diamond [8–10]. The thermal conductivity of single crystal diamond at room temperature is as high as 2200 W/(m·K), five times that of copper and ten times that of aluminum. In addition, diamond possesses an extremely high hardness, high elastic modulus, low thermal expansion coefficient, low density, outstanding radiation resistance, and stable physical and chemical properties. Furthermore, it exhibits low mass loss in a vacuum and produces no condensable volatiles. Thus, it is an ideal material for aerospace applications. Synthetic diamonds have attracted enthusiastic attention for applications in high-power lasers, high-power traveling-wave tubes, terahertz antennas, heat dissipation in high heat flux GaN chips, high-performance radiation detectors, and high-power microwave windows. Application research has been carried out in some of these areas [10–23]. Over the past 30 years, the research on synthetic diamonds in China has achieved meaningful progress in some technical fields [24–26]. There are mainly three methods for fabricating large-size synthetic diamonds: hot filament chemical vapor deposition (CVD), direct current (DC) plasma jet CVD, and microwave plasma CVD. The hot filament CVD method dissociates H2 and CH4 at high temperatures by heating and deposits carbon elements. The DC plasma jet CVD method and the microwave plasma CVD method rely on the high temperature of the plasma or charged particles (electrons and ions) that collide with the molecules and atoms of H2 and CH4 to excite the precursor gases and deposit carbon elements to form a diamond structure. The hot filament CVD method can fabricate diamond discs with 180 mm diameters and 2 mm thicknesses, but it can hardly achieve materials thermal conductivities beyond 1000 W/(m·K) under fast growth condition [27]. The microwave plasma CVD method can fabricate high-quality single-crystal diamonds with thermal conductivities of more than 2000 W/(m·K), but the diamonds are small in size (< Ø70 mm) and too expensive. The DC plasma jet CVD method can fabricate high-quality polycrystalline diamonds with thermal conductivities of up to 2000 W/(m·K) at a moderate price [28, 29]. Based on the requirements of the satellite in terms of product size, thermal conductivity, and batch production capacity, the high-thermal-conductivity diamond investigated in this article was developed by the DC plasma jet CVD method.