This multi-contributor handbook discusses Molecular Beam Epitaxy (MBE), an epitaxial deposition technique which involves laying down layers of materials with atomic thicknesses on to substrates. It ...summarizes MBE research and application in epitaxial growth with close discussion and a 'how to' on processing molecular or atomic beams that occur on a surface of a heated crystalline substrate in a vacuum. MBE has expanded in importance over the past thirty years (in terms of unique authors, papers and conferences) from a pure research domain into commercial applications (prototype device structures and more at the advanced research stage). MBE is important because it enables new device phenomena and facilitates the production of multiple layered structures with extremely fine dimensional and compositional control. The techniques can be deployed wherever precise thin-film devices with enhanced and unique properties for computing, optics or photonics are required. This book covers the advances made by MBE both in research and mass production of electronic and optoelectronic devices. It includes new semiconductor materials, new device structures which are commercially available, and many more which are at the advanced research stage.
Condenses fundamental science of MBE into a modern reference, speeding up literature reviewDiscusses new materials, novel applications and new device structures, grounding current commercial applications with modern understanding in industry and research Coverage of MBE as mass production epitaxial technology enhances processing efficiency and throughput for semiconductor industry and nanostructured semiconductor materials research community
Inductive components such as line filter inductors or transformers occupy a significant amount of space in today's power electronic systems, and furthermore, considerable losses occur in these ...components. A main application of inductive components is EMI filters, as, e.g., employed for the attenuation of switching frequency harmonics of power factor correction (PFC) rectifier systems. In this paper, a design procedure for the mains side LCL filter of an active three-phase rectifier is introduced. The procedure is based on a generic optimization approach, which guarantees a low volume and/or low losses. Different designs are calculated to show the tradeoff between filter volume and filter losses. The design procedure is verified by experimental measurements. Furthermore, an overall system optimization, i.e., an optimization of the complete three-phase PFC rectifier, is given.
Skin-like intrinsically stretchable soft electronic devices are essential to realize next-generation remote and preventative medicine for advanced personal healthcare
. The recent development of ...intrinsically stretchable conductors and semiconductors has enabled highly mechanically robust and skin-conformable electronic circuits or optoelectronic devices
. However, their operating frequencies have been limited to less than 100 hertz, which is much lower than that required for many applications. Here we report intrinsically stretchable diodes-based on stretchable organic and nanomaterials-capable of operating at a frequency as high as 13.56 megahertz. This operating frequency is high enough for the wireless operation of soft sensors and electrochromic display pixels using radiofrequency identification in which the base-carrier frequency is 6.78 megahertz or 13.56 megahertz. This was achieved through a combination of rational material design and device engineering. Specifically, we developed a stretchable anode, cathode, semiconductor and current collector that can satisfy the strict requirements for high-frequency operation. Finally, we show the operational feasibility of our diode by integrating it with a stretchable sensor, electrochromic display pixel and antenna to realize a stretchable wireless tag. This work is an important step towards enabling enhanced functionalities and capabilities for skin-like wearable electronics.
The primary developing trends in flexible and stretchable electronics involve the innovation of material synthesis, mechanical design, and fabrication strategies that employ soft substrates. The ...biggest challenge is that the entire electronic system must allow not only bending but also stretching. Therefore, stretchable conductors become a crucial construction unit for the connection of working circuits of various stretchable devices. Owing to the success of stretchable conductors, various stretchable electronic devices are fabricated with the help of multiple manufacturing strategies, including stretchable heaters, stretchable energy conversion and storage devices, stretchable transistors, sensors and artificial skin. The continuous development of stretchable electronics has led to the new functionality of transparency, and the fabrication of transparent stretchable electronic devices has gained a lot of interest due to the potential of wearable electronic systems. This review presents technology developments in the preparation of related materials, fabrication strategies and various applications of stretchable electronics. It focuses on the fundamental structural design, mechanisms, and tactics, as well as on challenges and opportunities in the manufacture of stretchable electronic devices and their various applications.
A nanoprocessor constructed from intrinsically nanometre-scale building blocks is an essential component for controlling memory, nanosensors and other functions proposed for nanosystems assembled ...from the bottom up. Important steps towards this goal over the past fifteen years include the realization of simple logic gates with individually assembled semiconductor nanowires and carbon nanotubes, but with only 16 devices or fewer and a single function for each circuit. Recently, logic circuits also have been demonstrated that use two or three elements of a one-dimensional memristor array, although such passive devices without gain are difficult to cascade. These circuits fall short of the requirements for a scalable, multifunctional nanoprocessor owing to challenges in materials, assembly and architecture on the nanoscale. Here we describe the design, fabrication and use of programmable and scalable logic tiles for nanoprocessors that surmount these hurdles. The tiles were built from programmable, non-volatile nanowire transistor arrays. Ge/Si core/shell nanowires coupled to designed dielectric shells yielded single-nanowire, non-volatile field-effect transistors (FETs) with uniform, programmable threshold voltages and the capability to drive cascaded elements. We developed an architecture to integrate the programmable nanowire FETs and define a logic tile consisting of two interconnected arrays with 496 functional configurable FET nodes in an area of ∼960 μm(2). The logic tile was programmed and operated first as a full adder with a maximal voltage gain of ten and input-output voltage matching. Then we showed that the same logic tile can be reprogrammed and used to demonstrate full-subtractor, multiplexer, demultiplexer and clocked D-latch functions. These results represent a significant advance in the complexity and functionality of nanoelectronic circuits built from the bottom up with a tiled architecture that could be cascaded to realize fully integrated nanoprocessors with computing, memory and addressing capabilities.
Power semiconductor devices based on silicon (Si) are quickly approaching their limits, set by fundamental material properties. In order to address these limitations, new materials for use in devices ...must be investigated. Wide bandgap materials, such as silicon carbide (SiC) and gallium nitride (GaN) have suitable properties for power electronic applications; however, fabrication of practical devices from these materials may be challenging. SiC technology has matured to point of commercialized devices, whereas GaN requires further research to realize full material potential. This review covers fundamental material properties of GaN as they relate to Si and SiC. This is followed by a discussion of the contemporary issues involved with bulk GaN substrates and their fabrication and a brief overview of how devices are fabricated, both on native GaN substrate material and non-native substrate material. An overview of current device structures, which are being analyzed for use in power switching applications, is then provided; both vertical and lateral device structures are considered. Finally, a brief discussion of prototypes currently employing GaN devices is given.
LLC resonant converter is one of the most suitable circuit topologies that have been introduced for designing constant output voltage switched-mode power supplies. In this paper, a design procedure ...is introduced for using this converter as a wide output range voltage source. Unlike constant output voltage applications which need small converter inductance ratio and narrow switching frequency variations, for wide output range applications, large values of these parameters are needed simultaneously and should be optimized. Instead of minimizing the components stresses, leading to a great value of the inductance ratio, proper choice of the converter parameters resulting in a smaller inductance ratio has been done. Maximum value of the capacitor in parallel with the power MOSFETs drain-sources has been derived to realize the zero voltage switching operation in the converter inductive region. Soft switching is achieved for all power devices under all operating conditions. A prototype of the converter has been tested for different regulated output voltages (35-165 V dc ) under different loads (0-3 A dc ) and input voltages (320-370 V dc ) for using an ion implanter arc power supply, with maximum efficiency value of 94.7%. Experimental results confirm the high performance of the wide output range LLC resonant converter even under the worst case conditions.
Low-resistivity metal–semiconductor (M–S) contact is one of the urgent challenges in the research of 2D transition metal dichalcogenides (TMDs). Here, we report a chloride molecular doping technique ...which greatly reduces the contact resistance (R c) in the few-layer WS2 and MoS2. After doping, the R c of WS2 and MoS2 have been decreased to 0.7 kΩ·μm and 0.5 kΩ·μm, respectively. The significant reduction of the R c is attributed to the achieved high electron-doping density, thus a significant reduction of Schottky barrier width. As a proof-of-concept, high-performance few-layer WS2 field-effect transistors (FETs) are demonstrated, exhibiting a high drain current of 380 μA/μm, an on/off ratio of 4 × 106, and a peak field-effect mobility of 60 cm2/(V·s). This doping technique provides a highly viable route to diminish the R c in TMDs, paving the way for high-performance 2D nanoelectronic devices.
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