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In this paper, we demonstrate a testing method for characterization of microgyroscopes using a virtual rate-table, which uses a series of voltage signals to emulate the Coriolis force induced by the angular rate inputs to obtain the frequency response of the gyroscope. The proposed approach holds the following advantages: 1) it provides a convenient and efficient way to evaluate the scale factor and bandwidth of the gyroscope operating in either open-loop mode or closed-loop mode, the laborious debugging by frequently utilizing the real rate-table can be avoided; 2) it can easily identify the dynamic response to external angular rate, which is the control plant during the rebalance control design for the sense mode in a large frequency range, avoiding the performance limit of the ordinary rate-table; and 3) it can be used in a self-test for the microgyroscope system for the error calibration and malfunction checking. The method was applied to a decoupled z -axis gyroscope. The test results show that the measured scale factor and bandwidth are 30.2 mV/(deg/s) and 8.0 Hz by the virtual rate-table method, which are in close agreement with the conventional rate-table method, i.e., 31.0 mV/(deg/s) and 7.4 Hz. The static calibration with the virtual rate-table was also evaluated. The scale factors measured with the conventional rate-table method and the virtual rate-table method are 31.0 mV/(deg/s) and 30.1 mV/(deg/s) with R2 nonlinearity of 0.03% and 0.02%, respectively. [ABSTRACT FROM PUBLISHER]

In this paper, the authors propose a butterfly-like multilayer microbridge, with heavily boron doped Si layer acting as the skeleton. Both microbridge sidewings are curved by intrinsic stress. The elasticity and deformation of the microbridge and its folded beam suspensions are theoretically analysed. When actuated by DC voltage, the sidewings snap down onto the coplanar waveguide (CPW) on the substrate first. With the further increase of the DC voltage, the central beam of the microbridge snaps onto the CPW signal plane, while the sidewings keep their shape. As a result, two metal-air-metal capacitors of nearly fixed value, between the microbridge and CPW ground planes, are formed. The ups and downs of 12 microbridges distributed along the CPW realize a binary variation of its insertion phase ( i.e. phase shift). The bulk Si fabrication process is shown. Optical test results confirm the anticipation of the deformation and action of the microbridges. The RF measurement shows a phase shift of 186° @ 20GHz can be achieved for a 6.3mm long phase shifter with a return loss under -8dB. [ABSTRACT FROM AUTHOR]

AlGaN/GaN metal oxide semiconductor high electron mobility transistors (MOSHEMTs) with thick (>35 nm), high-κ (TiO2/NiO), submicrometer-footprint (0.4 μm) gate dielectric are found to exhibit two orders of magnitude in lower gate leakage current (~1 nA/mm up to +3-V applied gate bias), higher IMAX (709 mA/mm), and higher drain breakdown voltage, compared to Schottky barrier (SB) HEMTs of the same geometry. The maximum extrinsic transconductance of both the MOSHEMTs and the SBHEMTs with 2 × 80-μm gate fingers is measured to be 149 mS/mm. The addition of the submicrometerfootprint gate oxide layer only results in a small reduction of the current gain cutoff frequency (21 versus 25 GHz, derived from S-parameter test data) because of the high permittivity (κ ≈ 100) of the gate dielectric. This high-performance submicrometer-footprint MOSHEMT is highly promising for microwave power amplifier applications in communication and radar systems. [ABSTRACT FROM AUTHOR]

This letter reports a silicon microcantilever sensor with an embedded n-type metal-oxide-semiconductor field-effect transistor (nMOSFET) for observing the kinetics of chemical molecules interaction based on surface stress sensing principle. In the sensors, the silicon cantilevers with gold coating and the channels of the embedded-nMOSFETs are configured along <100> crystal orientation. The kinetics of and the surface stress from chemical interactions between acetone, ethanol, nitroethane, and thiols molecules are observed, respectively, which follow the Langmuir model. The output signals of the nMOSFET-embedded cantilever sensors induced by various targets are different, which implies that the devices may allow for gaining insights into the kinetics of intermolecular interactions. [ABSTRACT FROM AUTHOR]

This letter presents a novel microelectromechanical system multifunction-integrated optical device capable of simultaneously operating as a variable optical power splitter (VOPS), optical switch (OS), and variable optical attenuator (VOA). Assembling with ball-lensed fibers, the device manipulates the light with a binary-slope mirror driven by compound electrostatic actuator. Measurements have revealed that the excess loss is less than 3 dB (VOPS state), the switching time is less than 9 ms (OS state), and the controllable attenuation range is up to 39 dB (VOA state). Moreover, excellent polarization-dependent loss performance is achieved. [ABSTRACT FROM PUBLISHER]

A test structure, which is called the ridge-furrow structure, is used to evaluate the leakage current of the Schottky contact on the mesa edge of an AlGaN/GaN heterostructure. The mesa edge leakage currents were measured at different temperatures from 300 to 500 K and analyzed. The conduction-band-edge energy distribution at the mesa edge is simulated by the Integrated Systems Engineering Technology Computer-Aided Design. Based on the simulation results, the electric field strength can be obtained as a function of reverse bias voltage. The mesa edge leakage current is found to agree with the predicted characteristics, which is based on the Frenkel-Poole emission model. Therefore, we believe that the Frenkel-Poole emission dominates the mesa edge leakage at temperatures between 300 and 500 K. [ABSTRACT FROM AUTHOR]

The effects of focused-ion-beam-induced damage on electrical properties of n-type Si are investigated by Schottky contacts. Crystalline Si is exposed to 10–30 keV focused ion beam (FIB), followed by Pt deposition under vacuum of 4×10-4 Pa. From current-voltage-temperature measurements, barrier heights of the Schottky contacts are found to increase almost linearly as the FIB energy increases, with the maximum increment of 0.29 eV. The increase is suggested to be related to the arising of acceptorlike defects and an amorphous layer due to FIB damages. A theoretical model is set up to quantitatively describe the barrier height changes. [ABSTRACT FROM AUTHOR]

This paper presents a novel concept of self-adaptive nonlinear stops (SANS) for the generic in-plane shock protection of microelectromechanical systems (MEMS) suspensions. This new shock protection strategy decouples the reliability design from the device design and is compatible with wafer-level MEMS batch fabrication without the requirement of additional processes or materials. SANS increase shock reliability by limiting the travel of the suspension in a compliant manner with efficient energy dissipation. Using numerical simulation, we analyzed the energy dissipation and the impact force between suspensions and shock stops under a half-sine shock impulse (3000 g (1 g  ≈  9.8 m s−2), 0.15 ms). The simulation results indicate that SANS can reduce approximately 89.4% of the impact force compared with hard stops, and additionally, dissipate more than 22.7% of the total mechanical energy in a round trip of the proof mass. To prove the improvement in shock protection, we designed and fabricated model test specimens of both SANS and conventional hard stops. The experimental results demonstrate that test specimens of SANS achieved twice the robustness compared with those of hard stops. [ABSTRACT FROM AUTHOR]

In this paper, a novel five-wire micro-fabricated anemometer with 3D directionality based on calorimetric principle is proposed, which is capable of measuring low speed airflow. This structure is realized by vertically bonding two different dies, which can be fabricated on the same wafer resulting in a simple fabrication process. Experiments on speed lower than 200 mm s−1 are conducted, showing good repeatability and directionality. The speed of airflow is controlled by the volumetric flow rate. The measured velocity sensitivity is 9.4 mV · s m−1, with relative direction sensitivity of 37.1 dB. The deviation between the expected and the measured directivity is analyzed by both theories and simulations. A correction procedure is proposed and turns out to be useful to eliminate this deviation. To further explore the potential of our device, we expose it to acoustic plane waves in a standing wave tube, showing consistent planar directivity of figure of eight. The measured velocity sensitivity at 1 kHz and 120 dBC is 4.4 mV · s m−1, with relative direction sensitivity of 27.0 dB. By using the correction method proposed above, the maximum angle error is about  ±2°, showing its good directionality accuracy. [ABSTRACT FROM AUTHOR]

The time-dependent threshold voltage drift induced by fast interface traps in a fully gate-recessed normally-off GaN MOSFET is studied. It is found that the degree and time scale of the shift in threshold voltage are consistent with the density and time constant of interface traps at the MOS interface. The device based on wet etching delivers higher interface quality and threshold voltage stability than that based on dry etching. Nitrogen deficiency and high oxygen coverage are considered to be the origins of the high interface trap density in the MOSFET fabricated by dry etching. [ABSTRACT FROM AUTHOR]

Threshold voltage drift under gate bias stress was investigated in gate-recessed enhancement mode (E-mode) GaN MOSFET and depletion mode (D-mode) GaN MOS high-electron-mobility transistor (MOSHEMT) with Al2O3 gate dielectric layer. Besides the positive shift of threshold voltage in both devices under positive gate stress, it is also found that positive shift could also exist in E-mode GaN MOSFET under negative gate bias stress, while negative shift is observed in D-mode MOSHEMT. A three-step trapping and detrapping process was observed in the drain current transient of the device after negative gate bias stress. It was suggested that gate electron injection and the following trapping in the “damaged” gate recessed GaN channel layer is the dominant mechanism for the positive shift of the threshold voltage under negative gate bias in the enhancement mode GaN MOSFET. [ABSTRACT FROM AUTHOR]

We report a novel multicontact radio frequency (RF) microelectromechanical system (MEMS) switch with mechanical independent switch elements and microspring contacts. The consistent contact arrangement and the robust contact design can effectively increase the contact area, reduce the current density, and therefore improve the power-current-handling capability. The working mechanism of the switch with microspring contact is investigated by CoventorWare®simulation tools. The switch, fabricated by the Cu–Ni dual-metallic-sacrificial-layer surface micromachining, is actuated at 55 V for characterization. The closing time is 11 s, and the opening time is 13.5 s. The isolation is –30.9 dB at 2 GHz and –11.5 dB at 20 GHz; the insertion loss is –0.12 dB at 2 GHz and –0.22 dB at 20 GHz. The contact metal is Pt–Au, and the measured switch resistance drops from 48 to 1.2 when the actuation voltage increases from 40 to 65 V. The switch element handles a current of 300 mA at 0.1 Hz. The switch is an excellent candidate for microwave applications requiring high-power handling. [ABSTRACT FROM AUTHOR]

A novel stacked Ti/Al based Ti/Al/Ti/Al/Ti/Al/Ti/Al/Ni/Au Ohmic contact structure is optimized. Compared with the conventional alloyed Ti/Al/Ni/Au Ohmic contact structure, the novel Ohmic contact structure can obtain much lower contact resistance and specific contact resistivity. Through analysis of x-ray diffraction spectra, cross-section transmission electron microscopy images and corresponding electron dispersive x-ray spectroscopy spectra in the novel stacked Ti/Al based Ohmic structure, the reactions between metals and the AlGaN layer were proven to be stable, uniform and continuous, which produced smooth contact interface. In addition, the top Au layer was prevented from diffusing downwards to the metal/AlGaN interface, which degraded the Ohmic performance. [ABSTRACT FROM AUTHOR]

The article discusses the study that demostrates the sorting of single gold nanoparticles through linear nanometer precision and synchronized optofluidic dual barriers. Topics mentioned include the optical manipulation of particles for biological and physical applications, the synchronization between flow drag force and optical force, and the application on tumor targeting and sorting of viruses and DNA particles.