Tuning the Active Oxygen Species of Two-Dimensional Borophene Oxide toward Advanced Metal-Free Catalysis.

Two-dimensional (2D) borophene materials are predicted to be ideal catalytic materials due to their structural analogy to graphene. However, the lack of chemical functionalization of borophene hinders its practical application in catalysis. Herein, we reported a massive production of freestanding few-layer 2D borophene oxide (BO) sheets with tunable active oxygen species by a moderate oxidation-assisted exfoliation method.

A High-Reliability RF MEMS Metal-Contact Switch Based on Al-Sc Alloy.

This paper presents a new metal-contact RF MEMS switch based on an Al-Sc alloy. The use of an Al-Sc alloy is intended to replace the traditional Au-Au contact, which can greatly improve the hardness of the contact, and thus improve the reliability of the switch. The multi-layer stack structure is adopted to achieve the low switch line resistance and hard contact surface.

Effects of Mask Material on Lateral Undercut of Silicon Dry Etching.

The silicon etching process is a core component of production in the semiconductor industry. Undercut is a nonideal effect in silicon dry etching. A reduced undercut is desired when preparing structures that demand a good sidewall morphology, while an enlarged undercut is conducive to the fabrication of microstructure tips.

Design and Fabrication of a Novel Poly-Si Microhotplate with Heat Compensation Structure.

I Microhotplates are critical devices in various MEMS sensors that could provide appropriate operating temperatures. In this paper, a novel design of poly-Si membrane microhotplates with a heat compensation structure was reported. The main objective of this work was to design and fabricate the poly-Si microhotplate, and the thermal and electrical performance of the microhotplates were also investigated.

A Novel Packaged Ultra-High Q Silicon MEMS Butterfly Vibratory Gyroscope.

A novel three-dimensional (3D) wafer-level sandwich packaging technology is here applied in the dual mass MEMS butterfly vibratory gyroscope (BFVG) to achieve ultra-high Q factor. A GIS (glass in silicon) composite substrate with glass as the main body and low-resistance silicon column as the vertical lead is processed by glass reflow technology, which effectively avoids air leakage caused by thermal stress mismatch. Sputter getter material is used on the glass cap to further improve the vacuum degree.

A High-Performance MEMS Accelerometer with an Improved TGV Process of Low Cost.

High-performance MEMS accelerometers usually use a pendulum structure with a larger mass. Although the performance of the device is guaranteed, the manufacturing cost is high. This paper proposes a method of fabricating high-performance MEMS accelerometers with a TGV process, which can reduce the manufacturing cost and ensure the low-noise characteristics of the device.

A critical evaluation of the catalytic role of CO in propane dehydrogenation catalyzed by chromium oxide from a DFT-based microkinetic simulation.

Propane dehydrogenation under CO is an important catalytic route to obtain propene with a good balance between selectivity and stability. However, a precise description of the catalytic role of CO in propane dehydrogenation is still absent. In this work, we focus on the elucidation of the role of CO by using DFT-based microkinetic simulation.

Revealing the role of HBr in propane dehydrogenation on CeO(111) DFT-based microkinetic simulation.

HBr, as a soft oxidant, has been demonstrated to have a good balance between stability and selectivity in catalytic propane dehydrogenation. However, the origin of enhancements induced by HBr (hydrobromic acid) remains elusive. In this study, DFT-based microkinetic simulations were performed to reveal the reaction pathway and performance of propane dehydrogenation catalyzed by CeO in the presence of HBr.

ZRO Drift Reduction of MEMS Gyroscopes via Internal and Packaging Stress Release.

Zero-rate output (ZRO) drift induces deteriorated micro-electromechanical system (MEMS) gyroscope performances, severely limiting its practical applications. Hence, it is vital to explore an effective method toward ZRO drift reduction. In this work, we conduct an elaborate investigation on the impacts of the internal and packaging stresses on the ZRO drift at the thermal start-up stage and propose a temperature-induced stress release method to reduce the duration and magnitude of ZRO drift.

A Novel High-Q Dual-Mass MEMS Tuning Fork Gyroscope Based on 3D Wafer-Level Packaging.

Tuning fork gyroscopes (TFGs) are promising for potential high-precision applications. This work proposes and experimentally demonstrates a novel high-Q dual-mass tuning fork microelectromechanical system (MEMS) gyroscope utilizing three-dimensional (3D) packaging techniques. Except for two symmetrically decoupled proof masses (PM) with synchronization structures, a symmetrically decoupled lever structure is designed to force the antiparallel, antiphase drive mode motion and eliminate low frequency spurious modes.

A Real-Time Circuit Phase Delay Correction System for MEMS Vibratory Gyroscopes.

With the development of the designing and manufacturing level for micro-electromechanical system (MEMS) gyroscopes, the control circuit system has become a key point to determine their internal performance. Nevertheless, the phase delay of electronic components may result in some serious hazards. This study described a real-time circuit phase delay correction system for MEMS vibratory gyroscopes.

A Novel Fabrication Method for a Capacitive MEMS Accelerometer Based on Glass-Silicon Composite Wafers.

In this paper, we report a novel teeter-totter type accelerometer based on glass-silicon composite wafers. Unlike the ordinary micro-electro-mechanical systems (MEMS) accelerometers, the entire structure of the accelerometer, includes the mass, the springs, and the composite wafer. The composite wafer is expected to serve as the electrical feedthrough and the fixed capacitance plate at the same time, to simplify the fabrication process, and to save on chip area.

Revealing the role of nitrogen dopants in tuning the electronic and optical properties of graphene quantum dots a TD-DFT study.

Graphene quantum dots (GQDs) have been suggested to have a wide range of applications due to their unique electronic and optical properties. Moreover, heteroatom doping has become a viable way to fine-tune the properties of GQDs. However, the working principle of the doping strategy is still not conclusive.

The Characteristics and Locking Process of Nonlinear MEMS Gyroscopes.

With the miniaturization of micro-electro-mechanical system (MEMS) gyroscopes, it is necessary to study their nonlinearity. The phase-frequency characteristics, which affect the start-up time, are crucial for guaranteeing the gyroscopes' applicability. Nevertheless, although the amplitude-frequency (A-f) effect, one of the most obvious problems in nonlinearity, has been well studied, the phase response of nonlinear gyroscopes is rarely mentioned.

A Novel Piezoresistive MEMS Pressure Sensors Based on Temporary Bonding Technology.

A miniature piezoresistive pressure sensor fabricated by temporary bonding technology was reported in this paper. The sensing membrane was formed on the device layer of an SOI (Silicon-On-Insulator) wafer, which was bonded to borosilicate glass (Borofloat 33, BF33) wafer for supporting before releasing with Cu-Cu bonding after boron doping and electrode patterning. The handle layer was bonded to another BF33 wafer after thinning and etching.

Halogenation of graphene triggered by heteroatom doping.

Halogenation is one of the most important ways to tailor the properties of graphene. We demonstrate for the first time that boron and nitrogen doping can effectively tune the interactions between halogen diatomic molecules and graphene from first principles calculations. Boron and nitrogen doping disrupt the regular pi-electron pattern and create spin density and orbital polarization.

A Resonant Z-Axis Aluminum Nitride Thin-Film Piezoelectric MEMS Accelerometer.

In this paper, we report a novel aluminum nitride (AlN) thin-film piezoelectric resonant accelerometer. Different from the ordinary MEMS (micro-electro-mechanical systems) resonant accelerometers, the entire structure of the accelerometer, including the mass and the springs, is excited to resonate in-plane, and the resonance frequency is sensitive to the out-plane acceleration. The structure is centrosymmetrical with serpentine electrodes laid on supporting beams for driving and sensing.

Research on the Protrusions Near Silicon-Glass Interface during Cavity Fabrication.

Taking advantage of good hermeticity, tiny parasitic capacitance, batch mode fabrication, and compatibility with multiple bonding techniques, the glass-silicon composite substrate manufactured by the glass reflow process has great potential to achieve 3D wafer-level packaging for high performance. However, the difference in etching characteristics between silicon and glass inevitably leads to the formation of the undesired micro-protrusions near the silicon-glass interface when preparing a shallow cavity etched around a few microns in the composite substrate. The micro-protrusions have a comparable height with the depth of the cavity, which increases the risks of damages to sensitive structures and may even trigger electrical breakdown, resulting in thorough device failure.

A Decoupling Design with T-Shape Structure for the Aluminum Nitride Gyroscope.

This paper reports a novel design for the decoupling of microelectromechanical systems (MEMS) gyroscopes. The MEMS gyroscope is based on piezoelectric aluminum nitride (AlN) film, and the main structure is a mass hung by T-shape beams. A pair of parallel drive electrodes are symmetrically placed on the surface of the vertical bar for driving the oscillating mass.

Research on a 3D Encapsulation Technique for Capacitive MEMS Sensors Based on Through Silicon Via.

A novel three-dimensional (3D) hermetic packaging technique suitable for capacitive microelectromechanical systems (MEMS) sensors is studied. The composite substrate with through silicon via (TSV) is used as the encapsulation cap fabricated by a glass-in-silicon (GIS) reflow process. In particular, the low-resistivity silicon pillars embedded in the glass cap are designed to serve as the electrical feedthrough and the fixed capacitance plate at the same time to simplify the fabrication process and improve the reliability.

Research on Wafer-Level MEMS Packaging with Through-Glass Vias.

A MEMS fabrication process with through-glass vias (TGVs) by laser drilling was presented, and reliability concerns about MEMS packaging with TGV, likes debris and via metallization, were overcome. The via drilling process on Pyrex 7740 glasses was studied using a picosecond laser with a wavelength of 532 nm. TGVs were tapered, the minimum inlet diameter of via holes on 300 μm glasses was 90 μm, and the relative outlet diameter is 48 μm.

Design and Simulation of A Novel Piezoelectric AlN-Si Cantilever Gyroscope.

A novel design of piezoelectric aluminum nitride (AlN)-Si composite cantilever gyroscope is proposed in this paper. The cantilever is stimulated to oscillate in plane by two inverse voltages which are applied on the two paralleled drive electrodes, respectively. The whole working principles are deduced, which based on the piezoelectric equation and elastic vibration equation.

PSPICE Hybrid Modeling and Simulation of Capacitive Micro-Gyroscopes.

With an aim to reduce the cost of prototype development, this paper establishes a PSPICE hybrid model for the simulation of capacitive microelectromechanical systems (MEMS) gyroscopes. This is achieved by modeling gyroscopes in different modules, then connecting them in accordance with the corresponding principle diagram. Systematic simulations of this model are implemented along with a consideration of details of MEMS gyroscopes, including a capacitance model without approximation, mechanical thermal noise, and the effect of ambient temperature.

Bandwidth optimization design of a multi degree of freedom MEMS gyroscope.

A new robust multi-degree of freedom (multi-DOF) MEMS gyroscope is presented in this paper. The designed gyroscope has its bandwidth and amplification factor of the sense mode adjusted more easily than the previous reported multi-DOF MEMS gyroscopes. Besides, a novel spring system with very small coupling stiffness is proposed, which helps achieve a narrow bandwidth and a high amplification factor for a 2-DOF vibration system.