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This paper presents the optimized design of membrane dimension and piezoresistors position to obtain a high performance of piezoresistive pressure sensor. The designs have been simulated by finite element analysis (FEA). For achieving high sensitivity and good linearity of pressure sensor with a measurement span of 4 MPa, we find that 25 µm thick and diameter of 600 µm for the membrane is required. The four resistors are aligned along a direction on a (001) plane membrane and located close to the rim where the pressure induced stress linearly depends on the pressure and is nearly close to the maximum stress along the membrane.

The experimental characterization for metal-insulator-semiconductor (MIS) capacitor by using the capacitance versus voltage (C-V) measurement is used to investigate the characteristics of dielectrics discharging in capacitive micro-actuator. The Al/SiNx/n-Si capacitors were prepared for experimantal measurement. The charge relaxation characteristics were obtained by the C-V measurements after different electrical stresses in the MIS capacitors. The experimental results show different discharging mechanisms for electron and hole in silicon-rich nitride films. The method is direct and simple to be used in assessing the dielectrics quality for reliable capacitive micro-actuators

For the first time, a metal-insulator-semiconductor (MIS) device that consists of silicon (Si) nanocrystals embedded in a silicon oxide film is proposed to investigate how the charge accumulation and relaxation can be manipulated by the nanocrystals for high reliable capacitive RF MEMS switch. A tri-layer structure, used as the insulator in our MIS device, comprises a thicker (about 100 nm) rapid thermal oxidation (RTO) silicon dioxide (SiO2) layer, a Si+SiO2 middle layer (about 100 nm) deposited by RF sputtering technique, and a RF-sputtered silicon dioxide capping layer. The electrical properties of the device have been characterized using capacitance versus voltage (C-V) measurements. The experiment results show a significant change of charge trapping and detrapping mechanisms in the composite insulator due to the presence of the Si nanocrystals in the middle layer. This result offers a possibility that the trapping or detrapping mechanisms in the dielectric can be manipulated by embedding nanocrystals in terms of materials (Ge, Si or other), density, size of nanocrystals and their distribution. It is anticipated that the charge trapping and their relaxation time in the dielectric of capacitive MEMS switch can be reduced.

Anodic bonding between glass wafer and Si wafer are widely used for micro-electro-mechanical system (MEMS) device fabrication and packaging due to the good bonding quality. The residual stress in the bonding interface, which results from the different thermal expansion coefficients of the two wafer materials, is depended on the bonding temperature. In MEMS piezoresistive pressure sensor, the residual stress in anodic bonding, which can affect the accuracy of the device, is investigated by using the finite element method (FEM). The piezoresistive pressure sensor performance is evaluated and the residual stress effect at different temperatures is investigated in this research. The simulation results show that anodic bonding residual stress affect piezoresistive pressure sensor accuracy significantly.

This paper presents the design and analysis of a piezoelectric lead zirconate titanate (PZT) thin film microcantilever operating in d 33 mode. The modal and harmonic response analysis of the PZT/ZrO 2 /SiO 2 /Si cantilever beam structure was implemented using the ANSYS software. The simulation results showed the dimensions of the cantilever and the interdigital electrode in terms of resonance frequency and generated output, respectively. The resonance frequencies of the structure were in the range of 3–18.6 kHz through the beam length from 2000 μm to 200 μm. The fabrication process of the cantilever was presented in detail with attention to the sol-gel process of both PZT and ZrO 2 films. The PZT thin films exhibit good ferroelectric properties with a remnant polarization of 20 μC/cm2.

In this paper, we demonstrate a p-n junction betavoltaic microbattery which is based on the wide-band gap material of GaN. Ni-63 was used as the pure beta radiant source. By the Monte Carlo (MC) simulation, the trajectories of single-energy electron beam incident on GaN target, the averaging penetration depth and the energy deposition along the penetration path were obtained. According to them, the optimal p-n junction depth was designed. To compare with the design, we have fabricated GaN betavoltaic cells using the metal-organic, chemical-vapor deposition (MOCVD) and the GaN micromachining technology. Under an activity of 11mCi Ni-63 source irradiation, the open circuit voltage of 25 mV and short circuit current of 2 nA were measured in a single 1∗1 cm cell which are far apart from designed values 475 mV and 56 nA. Methods to further increase the performance of the GaN betavoltaic microbattery were discussed.

Silicon infrared emitter was a key component in the infrared gas detection systems. In this paper, finite element thermal-electric simulation in ANSYS is used to simulate polysilicon infrared emitters based on silicon on insulator (SOI) technology. In the simulation, silicon infrared emitters were studied with respect to power consumption, response time, surface temperature distribution and thermal induced stress. Based on the results and discussion, a new bridge structure is proposed in order to optimize device performance.

This paper presents the design and simulation of energy harvesting system based on radioisotope. This energy generator is a typical spring-mass-damping system that converts nuclear energy into mechanical vibration energy. The vibration energy is converted into extricable electrical energy by a capacitive energy converter which consists of a top Pt electrode and a bottom Al electrode deposited on vibration mass. The two parallel electrodes with different work functions will generate a build-in voltage for initially charging the capacitor. A physical model is established. The simulation results show that the maximum average output power of the simple external load is 0.16 μW, when the surface power of the radioisotope is 1.28 μW. The energy conversion efficiency is 12.5%.

The unique emission of a metallic infrared (IR) emitter with hexagonal holes lattice structure has been reported in this paper. The emission spectrum of the IR emitter shows a strong narrow-band emission in middle infrared range. Though the positions of peaks of the emission and transmission spectra are almost coincide with each other, the transmission spectrum show sharper coupled effects than the emission spectrum and the strongest peak of the two spectrums is different. The coupled effect was analyzed in detail by the surface plasmon polaritons (SPPs) coupled dispersion model and the localized surface plasmon (LSP) theory. We found that the unique coupled effect is mainly depended on the excitation process of the LSP modes. The thermal image of the emitter shows that the substrate emission also has important interference in the emission spectrum.

In this paper, microgyroscopes using fully decoupled structure (FDS) and partially decoupled structure (PDS) were designed. They both consist of dual proof mass, sense frame and drive frame structure. Sense frame is directly anchored on the substrate in FDS. The cross talk between drive mode and sense mode was investigated. The ANSYS software has been used to simulate two types of decoupled Z-axis microgyroscopes for performance comparison. The cross-talk displacement ratio η Dts in FDS is 0.19% at the frequency of 6650 Hz and η Dts in PDS is 0.24% at the frequency of 5776 Hz. The results show that the FDS microgyroscopes have lower quadrature-error effect than PDS. The noise level of both FDS and PDS microgyroscopes are 0.362 deg/hr/√Hz and 0.44 deg/hr/√Hz, respectively.