Nano strain-amplifier: making ultra-sensitive piezoresistance in nanowires possible without the need of quantum and surface charge effects

This paper presents an innovative nano strain-amplifier employed to significantly enhance the sensitivity of piezoresistive strain sensors. Inspired from the dogbone structure, the nano strain-amplifier consists of a nano thin frame released from the substrate, where nanowires were formed at the centre of the frame. Analytical and numerical results indicated that a nano strain-amplifier significantly increases the strain induced into a free standing nanowire, resulting in a large change in their electrical conductance. The proposed structure was demonstrated in p-type cubic silicon carbide nanowires fabricated using a top down process. The experimental data showed that the nano strain-amplifier can enhance the sensitivity of SiC strain sensors at least 5.4 times larger than that of the conventional structures. This result indicates the potential of the proposed strain-amplifier for ultra-sensitive mechanical sensing applications.Comment: 4 pages, 5 figure

Thermoresistive properties of p-type 3C-SiC nanoscale thin films for high-temperature MEMS thermal-based sensors

We report for the first time the thermoresistive property of p-type single crystalline 3C-SiC (p-3C-SiC), which was epitaxially grown on a silicon (Si) wafer, and then transferred to a glass substrate using a Focused Ion Beam (FIB) technique. A negative and relatively large temperature coefficient of resistance (TCR) up to -5500 ppm K-1 was observed. This TCR is attributed to two activation energy thresholds of 45meV and 52 meV, corresponding to temperatures below and above 450 K, respectively, and a small reduction of hole mobility with increasing temperature. The large TCR indicates the suitability of p-3C-SiC for thermal-based sensors working in high-temperature environments

Piezoresistive effect in p-Type 3C-SiC at high temperatures characterized using Joule heating

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 of p-type silicon nanowires fabricated by a top-down process using FIB implantation and wet etching

The piezoresistive effect in silicon nanowires (SiNWs) has attracted a great deal of interest for NEMS devices. Most of the piezoresistive SiNWs reported in the literature were fabricated using the bottom up method or top down processes such as electron beam lithography (EBL). Focused ion beam (FIB), on the other hand, is more compatible with CMOS integration than the bottom up method, and is simpler and more capable of fabricating very narrow Si nanostructures compared to EBL and photolithography. Taking the advantages of FIB, this paper presents for the first time the piezoresistive effect of p-type SiNWs fabricated using focused ion beam implantation and wet etching. The SiNWs were locally amorphized by Ga+ ion implantation, selectively wet-etched, and thermally annealed at 700 °C. A relatively large gauge factor of approximately 47 was found in the annealed SiNWs, indicating the potential of using the piezoresistive effect in top-down fabricated SiNWs for developing NEMS sensors

3C-SiC on glass: an ideal platform for temperature sensors under visible light illumination

This letter reports on cubic silicon carbide (3C–SiC) transferred on a glass substrate as an ideal platform for thermoresistive sensors which can be used for in situ temperature measurement during optical analysis. The transfer of SiC onto an insulating substrate prevents current leakage through the SiC/Si junction, which is significantly influenced by visible light. Experimental data shows that the 3C–SiC on glass based sensor possesses a large temperature coefficient of resistance (TCR) of up to −7508 ppm K−1, which is about 10 times larger than that of highly doped Si. Moreover, the 3C–SiC based temperature sensor also outperforms low doped Si in terms of stability against visible light. These results indicate that 3C–SiC on glass could be a good thermoresistive sensor to measure the temperature of cells during optical investigations