Resonant tunnelling diodes （RTDs） have negative differential resistance effect, and the current-voltage characteristics change as a function of external stress, which is regarded as mesc-piezoresistance effect of RT...Resonant tunnelling diodes （RTDs） have negative differential resistance effect, and the current-voltage characteristics change as a function of external stress, which is regarded as mesc-piezoresistance effect of RTDs. In this paper, a novel micro-accelerometer based on AlAs/GaAs/In0.1Ga0.9As/GaAs/AlAs RTDs is designed and fabricated to be a four-beam-mass structure, and an RTD-Wheatstone bridge measurement system is established to test the basic properties of this novel accelerometer. According to the experimental results, the sensitivity of the RTD based micro-accelerometer is adjustable within a range of 3 orders when the bias voltage of the sensor changes. The largest sensitivity of this RTD based miero-accelerometer is 560.2025 mV/g which is about 10 times larger than that of silicon based micro piezoresistive accelerometer, while the smallest one is 1.49135 mV/g.展开更多
It is necessary to study the validation of strength models under planar shock loading in view of the fact that strength models for metals obtained at moderate strain rates are often used in the numerical simulations o...It is necessary to study the validation of strength models under planar shock loading in view of the fact that strength models for metals obtained at moderate strain rates are often used in the numerical simulations of shock wave phenomena. The variations of longitudinal stress, transverse stress and yield strength of oxygen-free high conductance （OFHC） copper with time under planar shock loading are obtained by using the manganin stress gauges and compared with the predicted results by the constructed seven constitutive models based on Y/G=constant and on G/B=constant （Y the yield strength, G the shear modulus, B the bulk modulus）, respectively. It seems that the pressure, density, temperature and plastic strain dependence of the yield strength for OFHC copper under planar shock loading is essential to the constitutive description.展开更多
Magnetron-sputtered MoS_(2) has applications in piezoresistive functional materials research owing to its unique nanostructure.However,the controlled incorporation of sulfur vacancies and realization of en-hanced piez...Magnetron-sputtered MoS_(2) has applications in piezoresistive functional materials research owing to its unique nanostructure.However,the controlled incorporation of sulfur vacancies and realization of en-hanced piezoresistive performance remain significant challenges.In this work,the direct growth of large-area MoS_(2) films with tunable sulfur vacancy concentrations was successfully achieved via magnetron sputtering at various temperatures.Microstructural analysis revealed that the application of strain al-tered the number of conductive channels between the vertical MoS_(2) nanosheets,changing the measured resistance and leading to excellent piezoresistive properties.More importantly,the unsaturated electrons due to the sulfur vacancies increased the in-plane carrier concentration of the MoS_(2)nanosheets.A de-position temperature of 50℃afforded the highest concentrations of sulfur vacancies and carriers.These MoS_(2)films possessed a carrier concentration of 6.58×10^(17)cm^(−3),which was 40.9%higher than that ob-tained at 150°C,and displayed superior piezoresistive performance.The films exhibited high gage factors of 2.66 and 23.22 under tensile and compressive strain of≤0.29%,respectively.These values were 118%and 323%higher,respectively,than those obtained for films deposited at 150°C.This work provides an effective route for modulating and mass producing MoS_(2)-based piezoresistive electronic devices.展开更多
This study proposes a novel design and micromachining process for a dual-cantilever accelerometer.Comb and curved-surface structures are integrated into the sensing structure to modulate the squeeze-film damping,thus ...This study proposes a novel design and micromachining process for a dual-cantilever accelerometer.Comb and curved-surface structures are integrated into the sensing structure to modulate the squeeze-film damping,thus effectively optimizing the response frequency bandwidth.Owing to the high stress concentration on the dual-cantilever integrated with a fully sensitive piezoresistive Wheatstone bridge,a high sensitivity to acceleration is achieved.In addition,the dual-cantilever accelerometer is fabricated using a specifically developed low-cost and high-yield(111)-silicon single-side bulk-micromachining process.The test results show that the proposed dualcantilever accelerometer exhibits a sensitivity of 0.086—0.088 mV/g/3.3 V and a nonlinearity of±(0.09%—0.23%)FS(full-scale).Based on dynamic characterization,an adequate frequency bandwidth of 2.64 kHz is verified.Furthermore,a resonant frequency of 4.388 kHz is measured,and a low quality factor(Q)of 7.62 is obtained,which agrees well with the design for air-damping modulation.The achieved high performance renders the proposed dual-cantilever accelerometer promising in applications such as automotive and consumer electronics.展开更多
基金supported in part by the National Natural Science Foundation of China (Grant No 50775209)the Fork Ying Tung Education Foundation (Grant No 101052)Program for Excellent Talents by Ministry of Education of China
文摘Resonant tunnelling diodes （RTDs） have negative differential resistance effect, and the current-voltage characteristics change as a function of external stress, which is regarded as mesc-piezoresistance effect of RTDs. In this paper, a novel micro-accelerometer based on AlAs/GaAs/In0.1Ga0.9As/GaAs/AlAs RTDs is designed and fabricated to be a four-beam-mass structure, and an RTD-Wheatstone bridge measurement system is established to test the basic properties of this novel accelerometer. According to the experimental results, the sensitivity of the RTD based micro-accelerometer is adjustable within a range of 3 orders when the bias voltage of the sensor changes. The largest sensitivity of this RTD based miero-accelerometer is 560.2025 mV/g which is about 10 times larger than that of silicon based micro piezoresistive accelerometer, while the smallest one is 1.49135 mV/g.
基金Supported by the National Natural Science Foundation of China under Grant No 10472048, and the Laboratory for Shock Wave and Detonation Physics Research, Institute of Fluid Physics, CAEP, under Grant No 9140C6702020603.
文摘It is necessary to study the validation of strength models under planar shock loading in view of the fact that strength models for metals obtained at moderate strain rates are often used in the numerical simulations of shock wave phenomena. The variations of longitudinal stress, transverse stress and yield strength of oxygen-free high conductance （OFHC） copper with time under planar shock loading are obtained by using the manganin stress gauges and compared with the predicted results by the constructed seven constitutive models based on Y/G=constant and on G/B=constant （Y the yield strength, G the shear modulus, B the bulk modulus）, respectively. It seems that the pressure, density, temperature and plastic strain dependence of the yield strength for OFHC copper under planar shock loading is essential to the constitutive description.
基金financially supported by the National Natural Science Foundation of China(11874267 and 51373036)the National Science Foundation for Young Scientists of China(61704107)。
基金supported by the National Natural Science Foundation of China(No.U20A201293)the Ningbo Ma-jor Special Project“Science and Technology Innovation 2025”(No.2020Z023),and the National Key Research and Development Pro-gram(No.2021YFB3201100).
文摘Magnetron-sputtered MoS_(2) has applications in piezoresistive functional materials research owing to its unique nanostructure.However,the controlled incorporation of sulfur vacancies and realization of en-hanced piezoresistive performance remain significant challenges.In this work,the direct growth of large-area MoS_(2) films with tunable sulfur vacancy concentrations was successfully achieved via magnetron sputtering at various temperatures.Microstructural analysis revealed that the application of strain al-tered the number of conductive channels between the vertical MoS_(2) nanosheets,changing the measured resistance and leading to excellent piezoresistive properties.More importantly,the unsaturated electrons due to the sulfur vacancies increased the in-plane carrier concentration of the MoS_(2)nanosheets.A de-position temperature of 50℃afforded the highest concentrations of sulfur vacancies and carriers.These MoS_(2)films possessed a carrier concentration of 6.58×10^(17)cm^(−3),which was 40.9%higher than that ob-tained at 150°C,and displayed superior piezoresistive performance.The films exhibited high gage factors of 2.66 and 23.22 under tensile and compressive strain of≤0.29%,respectively.These values were 118%and 323%higher,respectively,than those obtained for films deposited at 150°C.This work provides an effective route for modulating and mass producing MoS_(2)-based piezoresistive electronic devices.
基金National Key R&D Program of China(Nos.2016YFA0200800 and 2016YFA0200803)National Natural Science Foundation of China(Nos.61674160 and 61834007)。
文摘This study proposes a novel design and micromachining process for a dual-cantilever accelerometer.Comb and curved-surface structures are integrated into the sensing structure to modulate the squeeze-film damping,thus effectively optimizing the response frequency bandwidth.Owing to the high stress concentration on the dual-cantilever integrated with a fully sensitive piezoresistive Wheatstone bridge,a high sensitivity to acceleration is achieved.In addition,the dual-cantilever accelerometer is fabricated using a specifically developed low-cost and high-yield(111)-silicon single-side bulk-micromachining process.The test results show that the proposed dualcantilever accelerometer exhibits a sensitivity of 0.086—0.088 mV/g/3.3 V and a nonlinearity of±(0.09%—0.23%)FS(full-scale).Based on dynamic characterization,an adequate frequency bandwidth of 2.64 kHz is verified.Furthermore,a resonant frequency of 4.388 kHz is measured,and a low quality factor(Q)of 7.62 is obtained,which agrees well with the design for air-damping modulation.The achieved high performance renders the proposed dual-cantilever accelerometer promising in applications such as automotive and consumer electronics.
