Silicon carbide has recently been developed as a platform for optically addressable spin defects. In particular, the neutral divacancy in the 4H polytype displays an optically addressable spin-1 ground state and near-infrared optical emission. Here, we present the Purcell enhancement of a single neutral divacancy coupled to a photonic crystal cavity. We utilize a combination of nanolithographic techniques and a dopant-selective photoelectrochemical etch to produce suspended cavities with quality factors exceeding 5000. Subsequent coupling to a single divacancy leads to a Purcell factor of ∼50, which manifests as increased photoluminescence into the zero-phonon line and a shortened excited-state lifetime. Additionally, we measure coherent control of the divacancy ground-state spin inside the cavity nanostructure and demonstrate extended coherence through dynamical decoupling. This spin-cavity system represents an advance toward scalable long-distance entanglement protocols using silicon carbide that require the interference of indistinguishable photons from spatially separated single qubits.

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Purcell Enhancement of a Single Silicon Carbide Color Center with Coherent Spin Control.

A search of the recent literature reveals that there is a continuous growth of scientific publications on the development of chemical vapor deposition (CVD) processes for silicon carbide (SiC) films and their promising applications in micro- and nanoelectromechanical systems (MEMS/NEMS) devices. In recent years, considerable effort has been devoted to deposit high-quality SiC films on large areas enabling the low-cost fabrication methods of MEMS/NEMS sensors. The relatively high temperatures involved in CVD SiC growth are a drawback and studies have been made to develop low-temperature CVD processes. In this respect, atomic layer deposition (ALD), a modified CVD process promising for nanotechnology fabrication techniques, has attracted attention due to the deposition of thin films at low temperatures and additional benefits, such as excellent uniformity, conformability, good reproducibility, large area, and batch capability. This review article focuses on the recent advances in the strategies for the CVD of SiC films, with a special emphasis on low-temperature processes, as well as ALD. In addition, we summarize the applications of CVD SiC films in MEMS/NEMS devices and prospects for advancement of the CVD SiC technology.

Progresses in Synthesis and Application of SiC Films: From CVD to ALD and from MEMS to NEMS.

Owing to the superior properties of silicon carbide (SiC), such as higher breakdown voltage, higher thermal conductivity, higher operating frequency, higher operating temperature, and higher saturation drift velocity, SiC has attracted much attention from researchers and the industry for decades. With the advances in material science and processing technology, many power applications such as new smart energy vehicles, power converters, inverters, and power supplies are being realized using SiC power devices. In particular, SiC MOSFETs are generally chosen to be used as a power device due to their ability to achieve lower on-resistance, reduced switching losses, and high switching speeds than the silicon counterpart and have been commercialized extensively in recent years. A general review of the critical processing steps for manufacturing SiC MOSFETs, types of SiC MOSFETs, and power applications based on SiC power devices are covered in this paper. Additionally, the reliability issues of SiC power MOSFET are also briefly summarized.

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Review of Silicon Carbide Processing for Power MOSFET

This paper presents the technological advancements of the electric vehicles (EVs) all over the world. The first emphasis is on the various types of the EVs along with the energy management strategies (EMSs). The EVs are equipped with different energy storage elements such as lithium-ion batteries, super capacitors (SCs) and fuel cells (FCs). Hence, it is important to optimize the power split between the various energy storage systems (ESSs) under the complex driving conditions. The second imperative aspect is the utilization of the energy efficient wide bandgap (WBG) semiconductor technology. The WBG materials present the superior properties like wide bandgap, high saturated drift velocity and high critical breakdown field. This has led a path for the development of SiC and GaN based power semiconductor devices (PSDs). However, this paper mainly focuses on the utilization of the SiC devices for the EV applications. The substantial features of the various SiC devices are presented along with the performance aggrandization methods. Furthermore, this paper presents the updated survey and various performance measures of the SiC based power converter topologies. It also emphasizes the necessity of energy optimization for the EV charging systems. On the other hand, the burning issues associated with the SiC power modules other than the power converters are explored in detail. This extensive literature survey provides insightness for the design and research engineers in view of fulfilling the research gaps between the current and the desired targets. 

A review on energy efficient technologies for electric vehicle applications

Temperature dependence of Young's modulus of single-crystal diamond determined by dynamic resonance

The significant advance of power electronics in today's market is calling for high-performance power conversion systems and MEMS devices that can operate reliably in harsh environments, such as high working temperature. Silicon-carbide (SiC) power electronic devices are featured by the high junction temperature, low power losses, and excellent thermal stability, and thus are attractive to converters and MEMS devices applied in a high-temperature environment. This paper conducts an overview of high-temperature power electronics, with a focus on high-temperature converters and MEMS devices. The critical components, namely SiC power devices and modules, gate drives, and passive components, are introduced and comparatively analyzed regarding composition material, physical structure, and packaging technology. Then, the research and development directions of SiC-based high-temperature converters in the fields of motor drives, rectifier units, DC-DC converters are discussed, as well as MEMS devices. Finally, the existing technical challenges facing high-temperature power electronics are identified, including gate drives, current measurement, parameters matching between each component, and packaging technology.

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Silicon Carbide Converters and MEMS Devices for High-temperature Power Electronics: A Critical Review

A single dc-link current sensor to reconstruct all three inverter phase currents has been proposed for the purpose of cost reduction and sensor fault tolerance in the motor drive. A novel phase current reconstruction scheme, with the immeasurable areas reduced, has been reported in the paper to tackle the problems caused by the presence of regions in the voltage vector plane where the phase currents are not directly measured. An active vector pulse insertion method achieves this objective by applying additional active voltage vectors in the brief intervals, and guaranteeing the invariant duty cycle in three-phase leg configuration during each fundamental frequency cycle. The effectiveness of the proposed reconstruction algorithm has been verified via a permanent magnet synchronous motor drive with 500 W rated power. Simulation and experimental results are provided to confirm the attractive performance characteristics of the resulting current reconstruction and regulation using the active vector pulse insertion method.

A three-phase current reconstruction technique using a single current sensor based on active vector pulse insertion

The dual-motor electric vehicle has a simple structure, which enables the front and rear wheels to obtain adhesion at the same time. It can improve the acceleration characteristics of the vehicle and achieve high efficiency of the system. To optimize the propulsion efficiency, a power allocation method is designed to determine the torque ratio between the front and rear axle motors. This paper proposes an efficiency-based optimal energy management strategy for dual-motor driven electric vehicles. In this way, the remaining battery state of charge is improved by reducing vehicle power loss. The energy consumption of the vehicle is firstly determined by drive cycles. The optimal distribution factor is calculated to minimize the system loss at each time sample. This determines distributions of the traction, regeneration, and mechanical braking forces between two motors. Simulation analysis is conducted under drive cycles of NEDC and WLTC. Results show that the method can reduce the total energy consumption of the system. With the proposed method, the braking energy recovery rate is improved, which also enhances the economy of the whole vehicle under different driving conditions.

Xiaorui Guo

Papers

Silicon Carbide Converters and MEMS Devices for High-temperature Power Electronics: A Critical Review

A three-phase current reconstruction technique using a single current sensor based on active vector pulse insertion

Loss Minimization Based Energy Management for a Dual Motor Electric Vehicle