The Piezoresistive Effect of SiC for MEMS Sensors at High Temperatures: A Review (original) (raw)
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Piezoresistive effect in p-type 3C-SiC at high temperatures characterized using Joule heating
Scientific reports, 2016
Cubic silicon carbide is a promising material for Micro Electro Mechanical Systems (MEMS) applications in harsh environ-ments and bioapplications thanks to its large band gap, chemical inertness, excellent corrosion tolerance and capability of growth on a Si substrate. This paper reports the piezoresistive effect of p-type single crystalline 3C-SiC characterized at high temperatures, using an in situ measurement method. The experimental results show that the highly doped p-type 3C-SiC possesses a relatively stable gauge factor of approximately 25 to 28 at temperatures varying from 300 K to 573 K. The in situ method proposed in this study also demonstrated that, the combination of the piezoresistive and thermoresistive effects can increase the gauge factor of p-type 3C-SiC to approximately 20% at 573 K. The increase in gauge factor based on the combination of these phenomena could enhance the sensitivity of SiC based MEMS mechanical sensors.
Piezoresistive Effect in 4H Silicon Carbide towards Mechanical Sensing in Harsh Environments
2018
The fast-growing demand for mechanical sensors in harsh environments (e.g. mining/deep oil explorations, power/chemical plants and space explorations) urges the development of advanced materials which can replace silicon to work in these conditions. The superior mechanical properties of 4H silicon carbide (4H-SiC) combined with the physical stability at high temperatures offer new capabilities to develop MEMS sensors for those challenging situations. The piezoresistive effect is positioned as one of the most significant sensing mechanisms used in MEMS/NEMS sensors to detect or monitor mechanical signals, such as pressure, inertia, acceleration and deflection. Additionally, the use of micromachined sensors enables the miniaturization and integration capabilities while requiring low power consumption and simple readout circuitries. The main goals of this thesis are to investigate the piezoresistive effect in p-type 4H-SiC and to develop 4H-SiC based sensors which can be utilised for m...
Recent Developments on Silicon Carbide Thin Films for Piezoresistive Sensors Applications
The purpose of this chapter is to present an overview of the deposition techniques of SiC films, summarizing the deposition conditions that affect the piezoresistive properties of these films, the influence of the temperature on their piezoresistive properties and comparing the performance of piezoresistive sensors based on SiC films with those based in other materials. Moreover, the chapter focus attention is on the development of pressure sensors and accelerometers based on SiC films with suited piezoresistive properties to substitute the silicon in the microfabrication of these sensors so as to extend their endurance under harsh environment.
Microsystem Technologies, 2012
The use of thin films as sensing elements for microsensor applications has been shown very attractive due to their low-cost fabrication, potential for integration with standard CMOS technologies and possibility of deposition on different substrate types. In particular, piezoresistive sensors based on thin films have been commonly developed because can be easily implemented using microfabrication processes and present the best relation between sensitivity and system complexity, which showing great advantages in term of device integration. In our previous works , we studied undoped and nitrogen-doped PECVD a-SiC thin films as alternative materials to replace the silicon piezoresistors in strain and pressure sensors for harsh environments. Here, we focused our attention on the piezoresistive properties of sputtered silicon carbide (SiC), diamond-like carbon (DLC) and titanium dioxide (TiO 2 ) thin films. These materials were evaluated in terms of sensitivity or gauge factor and of the influence of the temperature on this sensitivity, allowing a preliminary analysis of the applicability of these thin films in high temperature piezoresistive sensors.
Effects of the Substrate on Piezoresistive Properties of Silicon Carbide Thin Films
2000
Silicon carbide (SiC), in bulk or film form, has been shown as a promising material to replace the silicon as sensing element in devices for harsh environments. This has motivated several studies on growth and characterization of SiC thin films on different substrates such as silicon, silicon dioxide (SiO 2 ), aluminum nitride (AlN) and silicon nitride (Si 3 N 4 ), among others. However, less attention has been given to the investigation on how substrates affect the piezoresistive properties of SiC thin films. In this work, we have investigated the effect of substrates on the piezoresistive properties of SiC thin films produced by magnetron sputtering. Three types of substrates were utilized: (100) monocrystalline silicon, AlN on silicon and thermally oxidized silicon. Test structures were fabricated using photolithography, metallization lift-off and RIE (reactive ion etching) processes in order to perform piezoresistive characterization of the SiC samples produced.
Microsystem Technologies, 2011
In order to evaluate the potential of amorphous silicon carbide (a-SiC) films for piezoresistive sensors applications, a pressure sensor has been developed based on this material. The deposition conditions and properties of a-SiC films deposited on thermally oxidized (100) Si substrates by two techniques enhanced by plasma, PECVD (plasma enhanced chemical vapor deposition) and RF magnetron sputtering, are briefly described and compared. Among the SiC films produced, we choose the nitrogendoped PECVD SiC film to fabricate the piezoresistors of the sensor. The structure of the sensor consists of six a-SiC piezoresistors, configured in Wheatstone bridge, on a SiO 2 / Si square diaphragm. The sensor was tested for applied pressure ranging from 0 to 12 psi and supply voltage of 12 V. A preliminary study of the influence of the temperature on the performance of the sensor was performed by experimental measurements and theoretical investigations.
Piezoresistance behaviors of ultra-strained SiC nanowires
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